Transboundary River Water Availability to Ravi Riverfront under Changing Climate: A Step towards Sustainable Development

: The Indus Water Treaty allocated the water of the Ravi River to India, and India constructed the Thein Dam on the Ravi River. This study investigates the water availability of the Ravi Riverfront for both pre-dam and post-dam scenarios augmented with pre-ﬂood, ﬂood, and post-ﬂood sub-scenarios. The study also investigates river water availability for low and high magnitudes (Flow Duration Curves) and its linkages with climate change. The modiﬁed Mann–Kendall, Sen’s slope estimator, and Pearson correlation were used to investigate the river ﬂows. It was found that there is a remarkable decrease in the river water by − 36% of annual mean ﬂows as compared to the pre-dam scenario. However, during the ﬂood season, it was − 32% at the riverfront upstream (Ravi Syphon Gauge). The reduction in water volume was found as 2.13 Million Acre Feet (MAF) and 1.03 MAF for maximum and mean, respectively, in the Rabi (Winter) season, and 4.07 MAF and 2.76 MAF for max and mean, respectively, in the Kharif (Summer) season. It was also revealed that 180–750 cusecs of water would be available or exceeded for 90% to 99% of the time at Ravi Riverfront during the ﬂood season. The high ﬂows were mainly controlled by temperature in the pre-dam scenario; presently, this water is stored in the Thein Dam reservoir. In contrast, the precipitation role is signiﬁcant in the post-dam scenario, which means that the ﬂows in the Ravi River are mainly due to base ﬂow contributions and precipitation. This study is the ﬁrst step in analyzing the river water availability of the Ravi Riverfront, which will ultimately address the associated problems and their solutions to decision-makers. Additionally, implementing an eco-friendly riverfront promotes urban sustainability in developed urban areas, such as Lahore City, and will lead to a comfortable and healthy lifestyle; this will only be possible with water availability in the Ravi Riverfront reach.


Introduction
The hydrology of the Indus Basin is complex and sensitive to climate change and is a flood-prone zone.Additionally, the partition of the subcontinent has created conflict between India and Pakistan regarding the water distribution rights of the Indus Basin.Transboundary water issues of the Indus Basin were addressed with a temporary "Standstill agreement in 1947", the "Inter-Dominion Accord 1948", and eventually, the Indus Water Treaty in 1960 [1].The treaty covers six main rivers, the Indus, Jhelum, Chenab, Ravi, 2 of 23 Beas, and Sutlej, and their tributaries, known as the Indus River System [2].In the treaty, the exclusive water use rights for the three western rivers (Indus, Jhelum, and Chenab) were given to Pakistan, and the rest three eastern rivers (Ravi, Bias, and Sutlej) to India [3].However, five rivers (Jhelum, Chenab, Ravi, Sutlej, and Bias) finally join the Indus River at Panjnad Barrage, located in Punjab, Pakistan.
The Lahore district of Pakistan is exposed to the loss of biodiversity, the unplanned expansion of Lahore City, the lowing of the groundwater table at an accelerated rate, and extreme climatic events.As a part of the Lahore district, the Ravi River is facing similar problems regarding additional water stress due to the construction of the Thein Dam.The obstruction caused by the dam has been rehabilitated by the construction of a 46 km riverfront at the stretch of the Ravi River, a well-established global method.However, the story of riverfront projects has attracted contradictory views, with researchers emphasizing the "vitality of rivers" in a natural state.These conflicting views demand an in-depth analysis of the riverfront focusing on biology, water quality, and eco-hydrology and their relationship with the ecosystem.
Table 1 summarizes the previous studies conducted in the Ravi River Basin alongside their major themes.In previous studies, most of these researchers focused on water pollution, water quality, groundwater contamination, ecosystems, glaciers, and an inventory of glacierized areas in Pakistan.
Table 1.Previous studies conducted in the Ravi River Basin between India and Pakistan.

Study Area (India/Pakistan) Main Theme References
Ravi River, Pakistan Microplastic pollution and its impacts on fish species [4] Ravi River, Lahore-Pakistan Arsenic contamination in shallow aquifers [5] Ravi River, Lahore-Pakistan The implication of microplastics on the riverine population [6] Ravi River, Pakistan Chromium and Lead Bioaccumulation in Cirrhina mrigala in the Water and Sediments [7] Ravi River Valley, India Climate tectonic landform evolution in NW Himalaya [8] Near Lahore, Pakistan Health risk assessment associated with irrigation water of heavy metal contamination [9] Ravi River, Lahore-Pakistan Microplastic burden [10] Jammu Kashmir, India Liquefaction hazard assessment in a seismically active region of the Himalayas [11] Chenab and Ravi River, India Variability in freshwater prawn populations of Macrobrachium dayanum [12] Himachal Pradesh, India Landslide slope stability [13] Ravi River, Lahore-Pakistan Assessment of community vulnerability to floods [14] Ravi and Sutlej River, Pakistan Terrestrial Determinants impact river water quality [15] Hudiara Drain, Ravi River, Pakistan Metal micronutrients and their depletion in Transboundary Drain [16] Lahore City, Pakistan Anthropogenic Activities in Lahore City aquifer.[17] Ravi River, Pakistan Quality and economic evaluation of groundwater [18] Himachal Pradesh Ravi River, India Heavy metal contamination and its adverse impacts on river fish [19] Beas and Ravi River, India Climate-induced erosions and tectonics in NW Himalaya [20] Glacierized area of Ravi Basin, India Glacial meltwater hydrogeochemical study [21] Jhok Forest, along the Ravi River, Pakistan Ecological status of a reserve forest in low flooded riparian [22] Ravi River, Lahore Pakistan Movement of arsenic in groundwater [23] Ravi, Beas, and Sutlej Rivers, India Arsenic contamination in the flood plains of India [24] Table 1.Cont.

Study Area (India/Pakistan) Main Theme References
Bari Doab, Ravi River India Arsenic presence in groundwater and associated health problems [25] Ravi Rive, Pakistan Microplastic pollution in Ravi River, Lahore [26] Thein Dam Project, India Thein Dam resettlement in India [27] Ravi River, Pakistan Floating wetlands are a treatment for polluting river water [28,29] Ravi River, Pakistan Accumulation of heavy metal contamination from Ravi Syphon to Balloki Barrage [30] Sutlej and Ravi River, Pakistan Water quality of Ravi and Sutlej River [31] Ravi River Basin, India Landslide hazard assessment in Chamba Region, Himalaya [32] Ravi River, Pakistan Pollution control concentration on enhancing the water quality of rivers [33] Ravi catchment, India Landslide hazard mapping in Himachal Pradesh, India [34] Ravi River, Lahore-Pakistan Wastewater quality of four drains entering the Ravi River [35] Glacierized area of Ravi Basin, India Glacier inventory in Ravi basin, western Himalaya [36] Thein Dam, Ravi River, India Water quality of the Thein Dam wetlands, India [37] Ravi syphon to Balloki, Pakistan presence and potent source of pesticides and specific pesticide-bearing effluent release points on the Ravi River, [38] Ravi River, Pakistan Metals concentration at Balloki Barrage [39] Ravi River, Lahore-Pakistan Urban effluents impact on mineral concentrations [40] Ravi River, Pakistan Arsenic presence in the Ravi River [41] Ravi River, India Snow cover distribution in central and western Himalayas [42] Ravi River, Pakistan Dissolved oxygen modeling in the Ravi River [43] Ravi River, Pakistan Heavy metal contamination in the Ravi River [44,45] Ravi Catchment, India Snow distribution in the western Himalayas [46] Chenab, Ravi, Beas, and Sutlej Variations in streamflow patterns in Northwestern Himalaya [47] In addition, Sahu et al. [48] investigated the hydropower potential of Himalayan rivers in India and their climate implications.The frontal changes in the Manimahesh and Tal Glaciers located at the source reach of the Ravi River were investigated by Chand and Sharma [49].Likewise, Aslam et al. (2020) [50] analyzed fourteen extreme climatic parameters in the Ravi River Basin using the observed temperature and precipitation in India and Pakistan and concluded an increased probability of warm and wet extremes.
The above literature indicates that a detailed study of the hydrology and variability of Ravi River water should have been addressed and received proper investigation in Pakistan.Therefore, this study presents a detailed understanding by focusing on the following: (i) changes in the river water availability for flood, pre-flood, and post-flood seasons; (ii) water availability to the riverfront from the perspective of pre-and post-Thein Dam scenarios; (iii) water variations in the pre-and post-Dam scenarios for Kharif (Summer) and Rabi (Winter) seasons; and (iv) Flow Duration Curves (FDCs) for the river gauges along the Ravi Riverfront and their correlations with climatic and groundwater parameters.

Study Area
The Ravi River is a transboundary river of the Indus River System originating from the northeast of Kangra district in Himachal Pradesh and southeast of the Chamba district in the Jammu Kashmir Region of India [36].The Ravi River enters Pakistan after flowing for a distance of 100 km from the upper catchments in India and drains into the Ravi plains at Nainkot, Pakistan (Figure 1a,b).The climate around the Ravi riverfront (Ravi Basin) is semi-tropical.The northern part receives more rainfall than the western part.The maximum snowmelt runoff occurs from April to June [1] and does not join the monsoon precipitation spells during July, August, and September in the Ravi River Basin.The Ravi River Basin has a semi-arid tropical climate.The upper sub-basins of the Ravi River Basin receive heavy rainfall in the northeast [50].The rainfall pattern varies throughout the year in a bimodal pattern (more rain in the summer season and least rainfall during November to January), which the EI Nino-Southern Oscillation greatly influences [50,51].The average annual temperature varies from 8 • C to 40 • C, and the average annual precipitation ranges from 300 mm to 1200 mm.The average annual flows are 208-1709 m 3 /s, mainly contributed by snowmelt and monsoon rainfall [50].

Study Area
The Ravi River is a transboundary river of the Indus River System originating from the northeast of Kangra district in Himachal Pradesh and southeast of the Chamba district in the Jammu Kashmir Region of India [36].The Ravi River enters Pakistan after flowing for a distance of 100 km from the upper catchments in India and drains into the Ravi plains at Nainkot, Pakistan (Figure 1a,b).The climate around the Ravi riverfront (Ravi Basin) is semitropical.The northern part receives more rainfall than the western part.The maximum snowmelt runoff occurs from April to June [1] and does not join the monsoon precipitation spells during July, August, and September in the Ravi River Basin.The Ravi River Basin has a semi-arid tropical climate.The upper sub-basins of the Ravi River Basin receive heavy rainfall in the northeast [50].The rainfall pattern varies throughout the year in a bimodal pattern (more rain in the summer season and least rainfall during November to January), which the EI Nino-Southern Oscillation greatly influences [50,51].The average annual temperature varies from 8 ℃ to 40 ℃, and the average annual precipitation ranges from 300 mm to 1200 mm.The average annual flows are 208-1709 m 3 /sec, mainly contributed by snowmelt and monsoon rainfall [50].

Data Collection
The Ravi Syphon is the first hydraulic structure in Pakistan.The Ravi Urban Development Authority proposed a 46 km planned riverfront city known as the Ravi Riverfront Urban Development Project (RRUDP) on both banks of the Ravi River in Lahore City (Figure 1c).There are two stream gauging stations within the 46 km stretch of RRUDP.The daily data of the Ravi River flows were collected from the Punjab Irrigation Department

Data Collection
The Ravi Syphon is the first hydraulic structure in Pakistan.The Ravi Urban Development Authority proposed a 46 km planned riverfront city known as the Ravi Riverfront Urban Development Project (RRUDP) on both banks of the Ravi River in Lahore City (Figure 1c).There are two stream gauging stations within the 46 km stretch of RRUDP.The daily data of the Ravi River flows were collected from the Punjab Irrigation Department from 1991 to 2015 for the Ravi Syphon and Shahdara gauging stations (Figure 1c).There are two climatic stations installed within the Ravi Basin.The daily data (1991-2015) of the maximum temperature, minimum temperature, and precipitation were obtained from the Pakistan Meteorological Department.

Experimental Design
The complete approach adopted in this study is presented in Figure 2. We divided the whole time series of the river flows into three main periods, as follows: annual (1991-2015), pre-flood (February to May), flood (June to September), and post-flood (October to January) seasons.These seasons were analyzed in the context of the Thein Dam in the Ravi Basin.
Pakistan Meteorological Department.

Experimental Design
The complete approach adopted in this study is presented in Figure 2. We divided the whole time series of the river flows into three main periods, as follows: annual (1991-2015), pre-flood (February to May), flood (June to September), and post-flood (October to January) seasons.These seasons were analyzed in the context of the Thein Dam in the Ravi Basin.

Data Analysis
The non-parametric Modified Mann-Kendall (MMK) trend test [52] was used to find the trends in the annual, flood, and pre-and post-flood seasons.The MMK trend test has

Data Analysis
The non-parametric Modified Mann-Kendall (MMK) trend test [52] was used to find the trends in the annual, flood, and pre-and post-flood seasons.The MMK trend test has been widely used in mountainous as well as plain areas and has well-established findings [53,54].
where n is the number of observations and ρk is the autocorrelation function for the rank of the observations.The significant values of ρk are used to calculate a correction factor n n * s .If a dataset is positively autocorrelated, it represents that the variance of S is underestimated.In this study, the 0.05 significance level was tested to check the significance of the trend.Additionally, the slope of this trend line was calculated using Sens's estimator [55].
The Pearson correlation analysis was used to estimate the correlation coefficients between the flows and the annual mean surface air temperature anomaly and annual mean precipitation [56] in the gauges within the boundary of the Ravi Riverfront.

Flow Duration Curves (FDC)
The flow duration curve indicates flow availability and the percentage of the equal or exceedance over a specific period in that river basin [57][58][59].FDCs have been widely used in almost all types (i.e., mountainous, cold regions, semi-arid to arid regions) of river basins for hydrological analysis [60][61][62][63][64][65][66].Generally, any FDC graph contains the flow on the Y-axis, whereas the X-axis includes the number of days exceedance from a particular flow-relative percentile flow [57,58].Q10, Q20, and Q30 show the flow percentile exceedance at 10, 20, and 30%, respectively.Q10 has high flows compared to Q20, and Q20 shows high flows compared to Q30 [57,58,67].The ratio of Q90 to Q50 (Q90/Q50) is the groundwater contribution to the total runoff [68,69], and the ratio of Q75 to Q50 (Q75/Q50) represents the total groundwater storage to runoff [67].In this study, the FDCs for the pre-dam, post-dam, and no-dam scenarios have been plotted and analyzed for the pre-flood, flood, and post-flood seasons at the gauges within the jurisdictions of the RRUDP.

No Dam Scenario
Figure 3 shows the trends in the river flows at the Ravi Syphon gauging station during annual, pre-flood, flood, and post-flood seasons.Maximum, minimum, and mean flows of 18,760.6,4844.12, and 9554.9 (ft 3 /s) per year were observed, respectively, in the annual time series.However, the annual time series  shows that the flow is decreasing significantly (p < 0.05) at a rate of −380.98 (ft 3 /s) per year.The pre-flood season (February to May) shows the maximum, minimum, and mean flows of 20,148.78,322.84, and 5576.36 (ft 3 /s), respectively.The flow significantly (p < 0.05) decreases during the pre-flood season with a trend magnitude of −273 (ft 3 /s) per year.The highest significantly reducing trend magnitude of flows was estimated during the flood season (June to September) with a magnitude of −60.256 (ft 3 /s) per year, while the maximum, minimum, and mean flows were recorded as 32,053, 12,118, and 20,567, respectively.The flows during the post-flood season (October to January) also decreased significantly, with a magnitude of −140.78 (ft 3 /s) per year.The maximum, minimum, and mean flows during the post-flood season were observed to be 8168, 585, and 2520 (ft 3 /s), respectively.In general, it can be concluded that the water inflow to the RRUDP at Ravi Syphon is significantly decreasing in all pre/post-flood seasons as well as during flood seasons; however, a steeper falling trend slope was calculated during the flood seasons, as presented in Figure 3.
The river flow trends for the Shahdara Gauging station in terms of the annual (1991-2015), pre-flood, flood, and post-flood seasons are presented in Figure 4.The yearly time series shows a significantly negative trend, with a magnitude of −171.10 (ft 3 /s) per year.The pre-flood, flood, and post-flood seasons also estimated the decreasing flow significantly (p < 0.05) at the rates of −197, −251.17, and −49.8 ft 3 /s per year, respectively.The maximum, minimum, and mean flows during the seasons are also shown in Figure 4.

Thein Dam Scenario
The

Thein Dam Scenario
The Thein Dam became operational in March 2001.Therefore, we introduced the Thein Dam Scenario in the time series of 1991-2015 and divided the data into pre-dam (1991-31 March 2001) and post-dam scenarios (1 April 2001(1 April to 2015)).The analysis is presented in pre-dam and post-dam scenarios in the below sections.The river flow trends at the Shahdara gauging station for the pre-dam time series (1991-March 2001) are illustrated in Figure 6.The annual and pre-flood seasons showed decreasing trends with the rate of −700.37 and −859.38 ft 3 /sec per year, respectively.However, the flood and post-flood seasons showed increasing trends with the magnitude of 283.74 and 80.1 ft 3 /sec per year, respectively.The maximum, minimum, and mean flow values are also shown in Figure 6.The river flow trends at the Shahdara gauging station for the pre-dam time series (1991-March 2001) are illustrated in Figure 6.The annual and pre-flood seasons showed decreasing trends with the rate of −700.37 and −859.38 ft 3 /s per year, respectively.However, the flood and post-flood seasons showed increasing trends with the magnitude of 283.74 and 80.1 ft 3 /s per year, respectively.The maximum, minimum, and mean flow values are also shown in Figure 6.

Post-Dam Scenario
The post-dam (Figure 7) results for the Ravi Syphon shows that the annual flows are decreasing with a slope of −142.01 ft 3 /s per year.A similar trend was observed for the pre-flood and flood seasons, with a magnitude of −13.73 and −298.86 ft 3 /s per year, respectively.There is only an increasing trend for the post-flood season (74.37 ft 3 /s per year).The maximum, mean, and minimum flow values for the Ravi Syphon are also shown in Figure 7.

Post-Dam Scenario
The post-dam (Figure 7) results for the Ravi Syphon shows that the annual flows are decreasing with a slope of −142.01 ft 3 /sec per year.A similar trend was observed for the pre-flood and flood seasons, with a magnitude of −13.73 and −298.86 ft 3 /sec per year, respectively.There is only an increasing trend for the post-flood season (74.37 ft 3 /sec per year).The maximum, mean, and minimum flow values for the Ravi Syphon are also shown in Figure 7.
Figure 8 illustrates the results of the post-dam scenario for the Shahdara gauging station during the annual, pre-flood, flood, and post-flood seasons.The river flows are decreasing for the annual, pre-flood, and flood seasons at −108.51, −5.26, and −245.74ft 3 /sec per year, respectively.Similar to the trends of the Ravi Syphon, the flows at Shahdara are also increasing at a rate of 69.06 ft 3 /sec per year (Figure 8).      Figure 9a shows a significantly decreasing trend volume of water in the pre-dam time series with a magnitude of −0.24 Million Acre Feet (MAF) per year.The post-dam time series showed that the volume of water recorded at the Ravi Syphon is increasing slightly (slope = 0.02 MAF per year) in the Rabi Season (see Figure 9b).However, it is evident from Figure 9a,b that there is a significant reduction in the maximum, minimum, and mean volume of water recorded at Ravi Syphon during the Rabi Season.
The volume of water recorded at the Shahdara Gauging station is also decreasing (−0.08 MAF per year) in the pre-dam time series for Rabi Season (Figure 9c).There is a slightly increasing trend with the same magnitude observed for Ravi Syphon (see Figure 9d).
(slope = 0.02 MAF per year) in the Rabi Season (see Figure 9b).However, it is evident from Figure 9a,b that there is a significant reduction in the maximum, minimum, and mean volume of water recorded at Ravi Syphon during the Rabi Season.
The volume of water recorded at the Shahdara Gauging station is also decreasing (−0.08 MAF per year) in the pre-dam time series for Rabi Season (Figure 9c).There is a slightly increasing trend with the same magnitude observed for Ravi Syphon (see Figure 9d).

Volume of Water in Pre-and Post-Dam Kharif Season
The volume of water recorded at the Shahdara Gauging station during the Kharif (Summer) Season in the pre-and post-dam scenario is presented in Figure 10.The volume of water recorded in the pre-dam and post-dam scenarios at the Ravi Syphon showed a decreasing trend magnitude of −0.4 MAF per year and −0.08 MAF per year, respectively.Similar trends but different magnitudes were also observed at the Shahdara Gauging station, as shown in Figure 10.The maximum, minimum, and mean volume of water for both scenarios are also described in Figure 10.

Flow Duration Curves
The following sections discussed the flow duration curves for high flows (Q10, Q20, and Q30), medium flow (Q50 and Q60), and low flows (Q75, Q90, and Q99) and their corresponding percentiles for no-dam, pre-dam, and post-dam scenarios during pre-flood, flood, and post-flood seasons.
of water recorded in the pre-dam and post-dam scenarios at the Ravi Syphon showed a decreasing trend magnitude of −0.4 MAF per year and −0.08 MAF per year, respectively.Similar trends but different magnitudes were also observed at the Shahdara Gauging station, as shown in Figure 10.The maximum, minimum, and mean volume of water for both scenarios are also described in Figure 10.

Flow Duration Curves
The following sections discussed the flow duration curves for high flows (Q10, Q20, and Q30), medium flow (Q50 and Q60), and low flows (Q75, Q90, and Q99) and their corresponding percentiles for no-dam, pre-dam, and post-dam scenarios during preflood, flood, and post-flood seasons.

No Dam Scenario
The FDCs for the pre-flood season showed that the low flow of 188 cusecs, 510 cusecs, and 1121 cusecs are available for 99%, 90%, and 75% of the time of the year at the Ravi Syphon, respectively.However, the high flows of 23437 cusecs, 18846 cusecs, and 13200 cusecs are available only for 10%, 20%, and 30% of the time of exceedance in a year, respectively (Figure 11a).

No Dam Scenario
The FDCs for the pre-flood season showed that the low flow of 188 cusecs, 510 cusecs, and 1121 cusecs are available for 99%, 90%, and 75% of the time of the year at the Ravi Syphon, respectively.However, the high flows of 23,437 cusecs, 18,846 cusecs, and 13,200 cusecs are available only for 10%, 20%, and 30% of the time of exceedance in a year, respectively (Figure 11a).
The maximum flow of 20,175 cusecs is only available for 10% of the time of exceedance, followed by 15,671 cusecs only for 20% of the time of exceedance (Figure 11d).The lower flows of 330 cusecs, 593 cusecs, and 1189 cusecs were available only for 99%, 90%, and 80% of the time of the year during the pre-flood season at Shahdara Gauging station (Figure 11d).During the flood season, Shahdara Gauging station observed that the high flow values of 20,653 cusecs were only available for 10% of the year; however, the lower values of flows 293 cusecs were available only for 99% of the time year (Figure 11e).The post-flood season recorded the high FDC of Q10 (20,480 cusecs) and Q20 (16,051 cusecs).In comparison, the lower flow values of 251 cusecs and 615 cusecs are available 99% and 90% of the year during the post-flood season (Figure 11f).lower flows of 330 cusecs, 593 cusecs, and 1189 cusecs were available only for 99%, 90% and 80% of the time of the year during the pre-flood season at Shahdara Gauging station (Figure 11d).During the flood season, Shahdara Gauging station observed that the high flow values of 20653 cusecs were only available for 10% of the year; however, the lowe values of flows 293 cusecs were available only for 99% of the time year (Figure 11e).The post-flood season recorded the high FDC of Q10 (20480 cusecs) and Q20 (16051 cusecs).In comparison, the lower flow values of 251 cusecs and 615 cusecs are available 99% and 90% of the year during the post-flood season (Figure 11f).The FDCs for the Ravi Syphon in the pre-and post-dam scenarios are presented in Figure 12.During the pre-flood season, the high flow magnitude of 27460 cusecs and 20320 cusecs are available for 10% of the time of exceedance in the pre-and post-dam scenarios The low flow FDCs of Q99, Q90, and Q75 were available as 182 cusecs, 472 cusecs, and 2106

Thein Dam scenario FDC for Ravi Syphon
The FDCs for the Ravi Syphon in the pre-and post-dam scenarios are presented in Figure 12.During the pre-flood season, the high flow magnitude of 27,460 cusecs and 20,320 cusecs are available for 10% of the time of exceedance in the pre-and post-dam scenarios.The low flow FDCs of Q99, Q90, and Q75 were available as 182 cusecs, 472 cusecs, and 2106 cusecs during the pre-dam scenario, respectively, whereas the flows of 194 cusecs, 487 cusecs, and 864 cusecs for the post-dam scenario at the Ravi Syphon (Figure 12a,b).The flow of 7491 cusecs and 2300 cusecs was available for 50% of the time of exceedance for the pre-and post-dam scenarios, respectively, at the Ravi Syphon during the flood season (Figure 12c,d).
and post-dam scenarios, respectively, at the Ravi Syphon during the flood season (Fig 12c,d).
The post-flood season showed that the high flow of 28760 cusecs (Q10), 23538 cus (Q20), and 18362 cusecs (Q30) in the pre-dam scenario, while the flow of 20816 cusecs (Q 16679 cusecs (Q20), and 11166 cusecs (Q30) in the post-dam scenario were available to Ravi Riverfront (Figure 12e,f).The high flows of 181 cusecs, 763 cusecs, and 193 cusecs, cusecs at 99% and 90% of the time of exceedance were available during the pre-and po dam scenarios, respectively.The flow of 6474 (2473 cusecs) was available for the aver time of exceedance (50%) during the pre(post)-dam scenarios in the post-flood season.

FDC for Shahdara Gauging Station
The flow duration curve (FDC) for the Shahdara Gauging station is presented in F ure 13.The maximum flows of 21331 cusecs followed by 17075 cusecs were only availa for 10% and 20% of the exceedance time in the pre-dam scenario during the pre-flo

FDC for Shahdara Gauging Station
The flow duration curve (FDC) for the Shahdara Gauging station is presented in Figure 13.The maximum flows of 21,331 cusecs followed by 17,075 cusecs were only available for 10% and 20% of the exceedance time in the pre-dam scenario during the pre-flood season at the Shahdara Gauging station (Figure 13a).However, the lower values of the flows of 336 cusecs and 1057 cusecs were available at 99% and 90%, respectively.The post-dam scenario showed that 337 cusecs and 560 cusecs covered 99% and 90% of the time of exceedance, respectively, during the pre-flood season (Figure 13b), while the high FDC obtained the 19,120 cusecs (Q10) and 15,069 cusecs (Q20).Fifty percent of the time of exceedance is available with 2239 cusecs in the post-dam scenario.low flow values were 333 cusecs and 298 cusecs for 99% of the time of exceedance under the pre-and post-dam scenarios (Figure 13c,d).Fifty percent of the time recorded the 5141 cusecs and 2548 cusecs for pre-and post-dam scenarios, respectively.
The post-flood season showed that the high flows of 23337 cusecs and 19289 cusecs were available for 10% of the time of exceedance under the pre-and post-dam scenarios.The lower flows of 418 cusecs and 259 cusecs were observed for 99% of the time of exceedance under the pre-and post-dam scenarios (Figures e,a,f).During the post-flood season, 50% of the time was covered with flows of 5010 cusecs and 2456 cusecs for pre-and postdam scenarios, respectively.The flood season recorded high flows of 22,478 cusecs and 19,115 cusecs for the preand post-dam scenarios, respectively, for 10% of the time of exceedance.In contrast, the low flow values were 333 cusecs and 298 cusecs for 99% of the time of exceedance under the pre-and post-dam scenarios (Figure 13c,d).Fifty percent of the time recorded the 5141 cusecs and 2548 cusecs for pre-and post-dam scenarios, respectively.
The post-flood season showed that the high flows of 23,337 cusecs and 19,289 cusecs were available for 10% of the time of exceedance under the pre-and post-dam scenarios.The lower flows of 418 cusecs and 259 cusecs were observed for 99% of the time of exceedance under the pre-and post-dam scenarios (Figure 13a,e,f).During the post-flood season, 50% of the time was covered with flows of 5010 cusecs and 2456 cusecs for pre-and post-dam scenarios, respectively.

Contribution of the Deepwater and Total Groundwater to Runoff
The percentile flows in the river reach of Ravi Riverfront vary for the Ravi Syphon and Shahdara Gauging stations under the pre-and post-dam scenarios for the pre-flood, flood, and post-flood seasons.However, Figure 14a depicts a remarkable decrease in the flow percentiles in the post-dam scenario compared to the pre-dam scenario for both gauges available within reach of the Ravi Riverfront.The maximum decrease was found in the Q50 (−69.3%),followed by Q60 (−67.18%) during the pre-flood season, Q60 (−65.37%) during the flood season, and Q50 (−61.1%) during the post-flood season, at Ravi Syphon.A similar trend was observed for the Shahdara Gauging station for Q60, followed by Q50 for pre-flood, flood, and post-flood scenarios but with different magnitudes (−61.65%,−59.58%, and −58.42%) and (−59.53%,−52.19%, and −52.87%).

Contribution of the Deepwater and Total Groundwater to Runoff
The percentile flows in the river reach of Ravi Riverfront vary for the Ravi Syphon and Shahdara Gauging stations under the pre-and post-dam scenarios for the pre-flood, flood, and post-flood seasons.However, Figure 14a depicts a remarkable decrease in the flow percentiles in the post-dam scenario compared to the pre-dam scenario for both gauges available within reach of the Ravi Riverfront.The maximum decrease was found in the Q50 (−69.3%),followed by Q60 (−67.18%) during the pre-flood season, Q60 (−65.37%) during the flood season, and Q50 (−61.1%) during the post-flood season, at Ravi Syphon.A similar trend was observed for the Shahdara Gauging station for Q60, followed by Q50 for pre-flood, flood, and post-flood scenarios but with different magnitudes (−61.65%,−59.58%, and −58.42%) and (−59.53%,−52.19%, and −52.87%).
The groundwater (Q90/Q50) and deepwater (Q75/Q50) contribution to runoff showed that the highest contribution occurred in the post-flood season for the Shahdara Gauge.In contrast, the groundwater contribution to runoff was high in the flood season (Figure 14b).The Ravi Syphon showed that the groundwater contribution (Q90/Q50) was high for the pre-flood season, whereas the deepwater contributions (Q75/Q50) were high during the flood season (Figure 14b).The groundwater (Q90/Q50) and deepwater (Q75/Q50) contribution to runoff showed that the highest contribution occurred in the post-flood season for the Shahdara Gauge.In contrast, the groundwater contribution to runoff was high in the flood season (Figure 14b).The Ravi Syphon showed that the groundwater contribution (Q90/Q50) was high for the pre-flood season, whereas the deepwater contributions (Q75/Q50) were high during the flood season (Figure 14b).

Climate Change Impact on River Flow
Figure 15 presents the Pearson correlation magnitudes for the pre-and post-dam scenarios relating to temperature, precipitation, and percentile river flows at the Ravi Syphon and Shahdara Gauging stations.For Ravi Syphon, the pre-dam scenario (Figure 15a) showed that the high flows (Q10, Q20, and Q30) were mainly controlled by the temperature as compared to precipitation, while precipitation is negatively correlated with high flows of Q10.The low flows (Q100, Q99, and Q90) have a relatively lesser dependency on temperature compared to high flows; however, the correlation is still more robust compared to precipitation (Figure 15a).The post-dam correlation results show (Figure 15b) that the temperature is positively correlated with high flows (Q10 to Q30), while precipitation is negatively correlated with the flows of Q20 and Q30.Moreover, the temperature is negatively correlated with low to medium flows (Q100 to Q50) as compared to precipitation, which is positively correlated with similar flows.Moreover, there is a high negative with temperature than with precipitation (Figure 15b).This shows that the flows available at the head of the Ravi Riverfront are mainly due to precipitation.A similar correlation was observed during pre-dam and post-dam scenarios for the Shahdara Gauging station, as shown in Figure 15c,d, respectively.It is also revealed that between Ravi Syphon and Shahdara Gauging stations, a stronger correlation exists for Ravi Syphon, and the temperature has a dominant impact on flows in the pre-dam scenario, while the impact of precipitation leads in the post-dam scenario.

Climate Change Impact on River Flow
Figure 15 presents the Pearson correlation magnitudes for the pre-and post-dam scenarios relating to temperature, precipitation, and percentile river flows at the Ravi Syphon and Shahdara Gauging stations.For Ravi Syphon, the pre-dam scenario (Figure 15a) showed that the high flows (Q10, Q20, and Q30) were mainly controlled by the temperature as compared to precipitation, while precipitation is negatively correlated with high flows of Q10.The low flows (Q100, Q99, and Q90) have a relatively lesser dependency on temperature compared to high flows; however, the correlation is still more robust compared to precipitation (Figure 15a).The post-dam correlation results show (Figure 15b) that the temperature is positively correlated with high flows (Q10 to Q30), while precipitation is negatively correlated with the flows of Q20 and Q30.Moreover, the temperature is negatively correlated with low to medium flows (Q100 to Q50) as compared to precipitation, which is positively correlated with similar flows.Moreover, there is a high negative with temperature than with precipitation (Figure 15b).This shows that the flows available at the head of the Ravi Riverfront are mainly due to precipitation.A similar correlation was observed during pre-dam and post-dam scenarios for the Shahdara Gauging station, as shown in Figure 15c,d, respectively.It is also revealed that between Ravi Syphon and Shahdara Gauging stations, a stronger correlation exists for Ravi Syphon, and the temperature has a dominant impact on flows in the pre-dam scenario, while the impact of precipitation leads in the post-dam scenario.

Discussion
This study focused on the transboundary Ravi River water availability to the Ravi Riverfront constructed along a 46 km stretch on both riverbanks.The study analyzed the water variations in pre-dam and post-dam scenarios after the construction of the Thein Dam in India at the Ravi River.The percentile of exceedance of river flows was also examined at the two hydrological gauging stations at Ravi Syphon and Shahdara within the riverfront stretch.Moreover, the association between the percentile flows and temperature and precipitation were also evaluated.Information sharing in the international rivers and shared river basins is one of the common challenges [70]; however, effective water treaties may reduce the conflict between countries and provide adequate water supplies to the downstream riparian countries [70][71][72].This study revealed that there was a remarkable change in the river flows before and after the operation of Thein Dam in March 2001.
The rapidly changing climate accelerates this issue and endangers several species due to a lack of ecological and environmental water flows in the downstream communities; this situation is quite similar to the Ravi River flows [73].Rapidly growing urbanization, water pollution, and depleting groundwater emphasize the smart living concept across the Ravi River, and the Govt. of Punjab took the initiative to build a riverfront along the river [74].Therefore, it is most important to explore the water availability, its variations, and linkages with the rapidly changing climate.There was a reduction of 40% of daily mean flows (−36% annual mean flows) recorder at the Ravi Syphon and a reduction of 29% of daily flows (−21% mean annual flows) for Shahdara Gauging Station between 1991 and 2015 due to the construction of the Thein Dam [73].However, the high flow season observed decreases of −32% and −18% for Syphon and Shahdara gauging stations, respectively.Aslam et al. [50] stated that there would be an increase in the extreme precipitations in the Ravi Basin.The results for the MK test in the basin show positive trends for all variables.Consequently, yearly variations in precipitation are greatly influenced by the local moisture recycling rate, which is controlled by planetary flow configurations linked with the El Niño-Southern Oscillation [75].
The variations in the volume of water availability of the Ravi Riverfront for the Rabi (Winter) and Kharif (Summer) seasons were also examined in the pre-and post-dam scenarios, which shows that there is a decrease of −2.13 MAF (−1.03 MAF) of maximum (mean) flow volume of water at Ravi Syphon and −1.64 MAF (−0.7 MAF) of maximum (mean) flow volume for Shahdara Gauge since the operation of the Thein Dam during the entire study period.These findings showed that the construction of dams in Indian territory without considering the ecological revival and downstream riparian [72,76] would cause a severe threat to communities living around the Ravi River.This is one of the common issues in transboundary river basins; however, the Indus Basin problems are the worst and most complex [72,77].
The flow duration curve showed that the flow ranging from 180 to 750 cusecs is available for 99 to 90% of the time of exceedance at Ravi Syphon in pre-and post-flood seasons.At the same time, there is the least difference for flows of Q90 and Q99 during flood season, which shows that most of the water is retained in the Thein Dam during flood season.There is precipitation as well as snowmelt runoff contributions in the flows [50].These agree with Adeyeri et al. [75] and [78], who reported separately that over land in the dry season with minimum high flows, there is a positive correlation between precipitation and temperature due to the low moisture-holding capacity of the atmosphere.The estimation of flows is very critical, especially in the ungauged river basins, and it has been a big challenge for the hydrologist from a planning and management perspective [65,79,80].The FDC form resulted from the geomorphological attributes and their interrelations [81], which are very complex.Adeyeri et al. [75] and Trenberth and Shea [82] further reported that wet summers, where high flows are at their maximum, are cool, thereby creating a negative relationship between wet season maximum temperature and precipitation.In the warm season, precipitation intensity is influenced by moisture availability rather than the atmospheric moisture storage capacity [83].Furthermore, the atmosphere has a high moisture-holding capacity, which reduces its rate of saturation during warmer summers.In the same vein, the local mechanism of moisture transport may also lower the supply of moisture during the wet season.Adeyeri et al. [83] and Berg et al. [78] confirmed that the process of drying soil in the wet seasons might also increase the temperatures.However, this contributory relationship is reversed in the dry months.
The high values in pre-flood flows recorded at the Ravi Syphon are only comparatively due to baseflow contributions (Q90/Q50).These rivers' vanishing flows and decreasing widths encourage encroachments for residential and industrial purposes.However, an episode of severe floods may wipe out these developments [1].In all seasons, the river discharge and precipitation have strong positive correlations.This may be attributed to the discharge increase as a result of the precipitation recovery [75,84].According to Trenberth and Shea [82] and Berg et al. [78], heavy precipitation intensity is enhanced by increasing temperature through increased atmospheric moisture, which drives the precipitation event through moisture convergence at low levels, as a consequence of the heavy precipitation intensity and discharge [75,83] and flooding events.Additionally, a reduced irrigated agriculture, forest and grassland potentially reduced the rate of evapotranspiration and infiltration, as well as interception loss, meaning that more water is available for discharge downstream [83,85].In general, climate variability and human activities (in the form of dam construction, irrigation canals, etc.) are generally seen as the primary forces altering river discharge [86].
Moreover, it can also be concluded that the reduction in the flows will not only alter the river course as well as encourage the encroachments, as it is prominent in the case of the Ravi River at Lahore.Therefore, keeping in view the large variations in the river water, depleting groundwater, heavy metal contamination, and dumping of wastewater into Ravi River increase the immense need for the Ravi Riverfront initiative to address all these issues, and these are common issues for a stream flowing through a populated urban development [87][88][89].

Conclusions
This study was conducted for one of the neglected Ravi River basins of the Indus River System between India and Pakistan.The Ravi River passes through the highly urban populated city of Lahore in Pakistan and faces several problems, e.g., dying river life, wastewater pollution, groundwater contamination, garbage, and encroachment due to significantly decreased = flows in the last two decades.We use the daily data from 1991-2015 for the two hydrological gauges installed at Ravi Syphon and Shahdara within reach of Ravi Riverfront and analyzed the flow availability and its interlinkages with climatic during pre-and post-dam scenarios for the pre-flood (February to May), flood (June to September), and post-flood (October to January) seasons.We concluded that: Gauge for maximum and minimum flows since the operation of Thein Dam in the entire study period.5.It also revealed that there are only 180-750 cusecs of water available or exceeded to Ravi Riverfront for 99 to 90% of the time in a year in the pre-flood and post-flood seasons, whereas there is a negligible difference at Q90 and Q99 during flood season.6.During the flood season, most of the water is retained in the Thein Dam, and there is precipitation as well as snowmelt runoff contributions in the flows.The preflood flows recorded at the Ravi Syphon are only due to baseflow contributions (Q90/Q50) comparatively.7. The high flows (Q10, Q20, and Q30) are significantly controlled by temperature in the pre-dam.At the same time, during the post-dam scenario, these were controlled by precipitation.
This study is the first step towards assessing river water availability to the planned Ravi Riverfront will ultimately address the associated problems and their solutions to the decision-makers.Additionally, implementing eco-friendly promotes urban sustainability in developed urban areas, such as Lahore City, and will lead to a comfortable and healthy lifestyle.However, this will only be possible with water availability in the Ravi Riverfront reach.These findings showed that the construction of dams in the Indian territory without considering the ecological revival and downstream riparians is a serious threat, and there is a strong need for sustainable solutions.

Figure 1 .
Figure 1.(a) Ravi River Basin originating from Hindukush Karakoram Himalaya, study area with Thein Dam and other stream network (b) and proposed riverfront and channelization (c).

Figure 1 .
Figure 1.(a) Ravi River Basin originating from Hindukush Karakoram Himalaya, study area with Thein Dam and other stream network (b) and proposed riverfront and channelization (c).

Figure 2 .
Figure 2. Conceptual layout of the methodology adopted in this research.

Figure 2 .
Figure 2. Conceptual layout of the methodology adopted in this research.
Thein Dam became operational in March 2001.Therefore, we introduced the Thein Dam Scenario in the time series of 1991-2015 and divided the data into pre-dam (1991-31 March 2001) and post-dam scenarios (1 April 2001 to 2015).The analysis is presented in pre-dam and post-dam scenarios in the below sections.

Figure 3 .
Figure 3. River water trends, mean, maximum, and average flows at annual, pre-flood, flood, and post-flood seasons at Ravi Syphon.Bold shows the significance at 0.05 confidence level.

Figure 4 .
Figure 4. River water trends, mean, maximum and average flows at annual, pre-flood, flood, and postflood seasons at Shahdara gauging station.Bold shows the significance at a 0.05 confidence level.

Figure 3 . 24 Figure 3 .
Figure 3. River water trends, mean, maximum, and average flows at annual, pre-flood, flood, and post-flood seasons at Ravi Syphon.Bold shows the significance at 0.05 confidence level.

Figure 4 .
Figure 4. River water trends, mean, maximum and average flows at annual, pre-flood, flood, and postflood seasons at Shahdara gauging station.Bold shows the significance at a 0.05 confidence level.

Figure 4 .
Figure 4. River water trends, mean, maximum and average flows at annual, pre-flood, flood, and post-flood seasons at Shahdara gauging station.Bold shows the significance at a 0.05 confidence level.
3.2.1.Pre-Dam ScenarioThe pre-dam river flows at Ravi Syphon are shown in Figure5.During the annual time series (1991-March 2001), the river flows show significant decreasing trends with a slope of −1262.19ft 3 /sec per year, followed by the pre-flood observed −1971.97ft 3 /sec per year, flood season magnitude of −592.48 ft 3 /sec per year and −350.53 ft 3 /sec per year during the post-flood period.The maximum, mean, and minimum flows are also shown in Figure5for the Ravi Syphon.

Figure 5 .
Figure 5. Pre-Dam water trends, mean, maximum, and average flows at annual, pre-flood, flood, and post-flood seasons at Ravi Syphon.Bold shows the significance at a 0.05 confidence level.

Figure 5 .
Figure 5. Pre-Dam water trends, mean, maximum, and average flows at annual, pre-flood, flood, and post-flood seasons at Ravi Syphon.Bold shows the significance at a 0.05 confidence level.

Figure 6 .
Figure 6.Pre-dam water trends, mean, maximum, and average flows during annual, pre-flood, flood, and post-flood seasons at Shahdara station.Bold shows the significance at a 0.05 confidence level.

Figure 6 . 24 Figure 7 .
Figure 6.Pre-dam water trends, mean, maximum, and average flows during annual, pre-flood, flood, and post-flood seasons at Shahdara station.Bold shows the significance at a 0.05 confidence level.Sustainability 2023, 15, x FOR PEER REVIEW 10 of 24

Figure 7 .
Figure 7. Post-dam streamflow trends, mean, maximum, and average flows during annual, pre-flood, flood, and post-flood seasons at Ravi Syphon.Bold shows the significance at a 0.05 confidence level.

Figure 8
Figure8illustrates the results of the post-dam scenario for the Shahdara gauging station during the annual, pre-flood, flood, and post-flood seasons.The river flows are decreasing for the annual, pre-flood, and flood seasons at −108.51, −5.26, and −245.74ft 3 /s per year, respectively.Similar to the trends of the Ravi Syphon, the flows at Shahdara are also increasing at a rate of 69.06 ft 3 /s per year (Figure8).

Figure 7 .
Figure 7. Post-dam streamflow trends, mean, maximum, and average flows during annual, preflood, flood, and post-flood seasons at Ravi Syphon.Bold shows the significance at a 0.05 confidence level.

Figure 8 .
Figure 8. Post-Dam streamflow trends, mean, maximum, and average flows during annual, preflood, flood, and post-flood seasons at Shahdara gauging station.Bold shows the significance at a 0.05 confidence level.

Figure 8 .
Figure 8. Post-Dam streamflow trends, mean, maximum, and average flows during annual, preflood, flood, and post-flood seasons at Shahdara gauging station.Bold shows the significance at a 0.05 confidence level.3.2.3.Rabi and Kharif Season Water Availability The Volume of Water in Pre-and Post-Dam Rabi Season The volume of water for the Rabi (winter) season and its trend for the pre-and postdam scenarios are shown in Figure 9 for the Ravi Syphon (a and b) and the Shahdara (c and d) Gauging station.Figure9ashows a significantly decreasing trend volume of water in the pre-dam time series with a magnitude of −0.24 Million Acre Feet (MAF) per year.The post-dam time series showed that the volume of water recorded at the Ravi Syphon is increasing slightly (slope = 0.02 MAF per year) in the Rabi Season (see Figure9b).However, it is evident from Figure9a,b that there is a significant reduction in the maximum, minimum, and mean volume of water recorded at Ravi Syphon during the Rabi Season.The volume of water recorded at the Shahdara Gauging station is also decreasing (−0.08 MAF per year) in the pre-dam time series for Rabi Season (Figure9c).There is a slightly increasing trend with the same magnitude observed for Ravi Syphon (see Figure9d).

Figure 9 .Figure 9 .
Figure 9. Pre-and post-dam river volume trends in Rabi (winter) season for Ravi Syphon and Shahdara gauging station.(a) and (b) shows the Pre and post-dam Syphon, (c) and (d) shows the pre and post-dam Shahdara.

Figure 10 .
Figure 10.Pre-and Post-Dam River Volume trends in Kharif (summer) season for Ravi Syphon and Shahdara gauging station.(a) and (b) shows the Pre and post-dam Syphon, (c) and (d) shows the pre and post-dam Shahdara.

Figure 10 .
Figure 10.Pre-and Post-Dam River Volume trends in Kharif (summer) season for Ravi Syphon and Shahdara gauging station.(a) and (b) shows the Pre and post-dam Syphon, (c) and (d) shows the pre and post-dam Shahdara.

Figure 11 .
Figure 11.Flow Duration Curves with no dam scenario (1991-2015) for Ravi Syphon and Shahdar Gauging stations during the pre-flood, flood, and post-flood seasons.(a), (b) and (c) indicates th pre-flood, flood and post-flood for Ravi Syphon, whereas (d), (e) and (f), respectively for Shahdara

Figure 11 .
Figure 11.Flow Duration Curves with no dam scenario (1991-2015) for Ravi Syphon and Shahdara Gauging stations during the pre-flood, flood, and post-flood seasons.(a), (b) and (c) indicates the pre-flood, flood and post-flood for Ravi Syphon, whereas (d), (e) and (f), respectively for Shahdara.

Figure 12 .
Figure 12.Flow Duration Curves at Ravi Syphon with pre-and post-dam scenario for Ravi Syp during pre-flood, flood, and post-flood seasons.(a), (c), and (e) shows the pre-flood, flood and p flood seasons in pre-dam, while (b), (d), and (f) for post-dam, respectively.

Figure 12 .
Figure 12.Flow Duration Curves at Ravi Syphon with pre-and post-dam scenario for Ravi Syphon during pre-flood, flood, and post-flood seasons.(a), (c), and (e) shows the pre-flood, flood and post-flood seasons in pre-dam, while (b), (d), and (f) for post-dam, respectively.

Figure 13 .
Figure 13.Flow duration curves at Shahdara Gauging Station with pre-and post-dam scenarios for Ravi Syphon during pre-flood, flood, and post-flood seasons.(a), (c), and (e) shows the pre-flood, flood and post-flood seasons in pre-dam, while (b), (d), and (f) for post-dam, respectively.

Figure 13 .
Figure 13.Flow duration curves at Shahdara Gauging Station with pre-and post-dam scenarios for Ravi Syphon during pre-flood, flood, and post-flood seasons.(a), (c), and (e) shows the pre-flood, flood and post-flood seasons in pre-dam, while (b), (d), and (f) for post-dam, respectively.