Environmental Flows Assessment in Nepal: The Case of Kaligandaki River
Abstract
:1. Introduction
1.1. Overview of E-Flow Concept
1.2. Environmental Flows Practices in Nepal
2. Materials and Method
2.1. Study Area
2.2. Methodology
2.2.1. Annual Distribution Method
2.2.2. Global Environmental Flow Calculator
2.2.3. Flow Duration Curve Analysis
2.2.4. Tennant Method
2.2.5. Dynamic Methods
2.2.6. Mean Annual Flow
2.2.7. Indicators of Hydrological Alteration (IHA) and Global Indexes
2.2.8. Environmental Flow Components
2.2.9. Limitations of the Methodology
3. Results
3.1. E-Fows Allocation
3.2. Interannual and Seasonal E-Flows Characterization
3.3. Flow Regime Alteration
3.3.1. IHA Alteration
3.3.2. E-flows Components (EFC)
4. Discussion
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Appendix A
IHA Parameters | Mean | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
30% Q-D | 10% MAF | Q80% | Q85% | Q90% | ADM | Class B | Class C | Class D | Class E | Class F | Tennant | |
Group #1 | ||||||||||||
July | 0.70 | 0.96 | 0.96 | 0.96 | 0.96 | 0.46 | 0.82 | 0.87 | 0.91 | 0.93 | 0.94 | 0.89 |
August | 0.70 | 0.97 | 0.97 | 0.97 | 0.97 | 0.46 | 0.85 | 0.90 | 0.92 | 0.94 | 0.95 | 0.91 |
September | 0.70 | 0.95 | 0.95 | 0.95 | 0.96 | 0.54 | 0.79 | 0.85 | 0.89 | 0.92 | 0.93 | 0.87 |
October | 0.70 | 0.90 | 0.89 | 0.90 | 0.91 | 0.50 | 0.54 | 0.68 | 0.77 | 0.82 | 0.85 | 0.79 |
November | 0.70 | 0.80 | 0.78 | 0.80 | 0.81 | 0.50 | 0.12 | 0.35 | 0.53 | 0.63 | 0.69 | 0.79 |
December | 0.70 | 0.70 | 0.68 | 0.70 | 0.72 | 0.50 | 0.03 | 0.10 | 0.30 | 0.45 | 0.54 | 0.70 |
January | 0.70 | 0.62 | 0.58 | 0.61 | 0.63 | 0.50 | 0.05 | 0.06 | 0.14 | 0.29 | 0.40 | 0.62 |
February | 0.70 | 0.55 | 0.51 | 0.54 | 0.57 | 0.52 | 0.05 | 0.06 | 0.08 | 0.18 | 0.29 | 0.55 |
March | 0.70 | 0.50 | 0.45 | 0.49 | 0.52 | 0.49 | 0.04 | 0.05 | 0.06 | 0.14 | 0.23 | 0.50 |
April | 0.70 | 0.54 | 0.50 | 0.54 | 0.56 | 0.46 | 0.04 | 0.06 | 0.10 | 0.20 | 0.30 | 0.35 |
May | 0.70 | 0.69 | 0.66 | 0.68 | 0.70 | 0.34 | 0.05 | 0.14 | 0.29 | 0.42 | 0.51 | 0.19 |
June | 0.70 | 0.89 | 0.88 | 0.88 | 0.89 | 0.43 | 0.51 | 0.64 | 0.73 | 0.79 | 0.82 | 0.67 |
Group #2 | ||||||||||||
1-day minimum | 0.70 | 1.10 | 0.09 | 0.07 | 0.06 | 0.02 | 0.69 | 0.00 | 0.00 | 0.02 | 0.06 | 0.32 |
3-day minimum | 0.70 | 0.39 | 0.34 | 0.38 | 0.42 | 0.42 | 1.00 | 1.00 | 0.00 | 0.03 | 0.10 | 0.39 |
7-day minimum | 0.70 | 0.41 | 0.35 | 0.40 | 0.43 | 0.42 | 1.00 | 0.00 | 0.00 | 0.04 | 0.11 | 0.41 |
30-day minimum | 0.70 | 0.46 | 0.41 | 0.45 | 0.48 | 0.46 | 1.00 | 0.02 | 0.03 | 0.09 | 0.18 | 0.46 |
90-day minimum | 0.70 | 0.51 | 0.47 | 0.50 | 0.53 | 0.47 | 1.00 | 0.03 | 0.05 | 0.14 | 0.24 | 0.51 |
1-day maximum | 0.70 | 0.99 | 0.99 | 0.99 | 0.99 | 0.64 | 1.00 | 0.96 | 0.97 | 0.98 | 0.98 | 0.97 |
3-day maximum | 0.70 | 0.99 | 0.98 | 0.98 | 0.99 | 0.59 | 0.93 | 0.95 | 0.96 | 0.97 | 0.98 | 0.96 |
7-day maximum | 0.70 | 0.98 | 0.98 | 0.98 | 0.98 | 0.53 | 0.91 | 0.94 | 0.95 | 0.96 | 0.97 | 0.94 |
30-day maximum | 0.70 | 0.97 | 0.97 | 0.97 | 0.97 | 0.51 | 0.87 | 0.91 | 0.94 | 0.95 | 0.96 | 0.92 |
90-day maximum | 0.70 | 0.96 | 0.96 | 0.96 | 0.96 | 0.49 | 0.83 | 0.88 | 0.91 | 0.93 | 0.94 | 0.89 |
Number of zero days | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
Base flow index | 0 | 4.580357 | 0.0008 | 0.000801 | 0 | 0.8071 | 1.455677 | 0.255647 | 0.253194 | 0.184867 | 0.080163 | 0.452621 |
Group #3 | ||||||||||||
Date of minimum | 0.000 | 0.94 | 0.90 | 0.94 | 0.94 | 0.05 | 0.00 | 0.000 | 0.000 | 0.148 | 0.475 | 1.000 |
Date of maximum | 0.00 | 0.18 | 0.18 | 0.18 | 0.18 | 0.03 | 0.18 | 0.18 | 0.185 | 0.178 | 0.178 | 0.183 |
Group #4 | ||||||||||||
Low pulse count | 0 | 1 | 0.988495 | 1 | 1 | 0.709692 | 0 | 0.067454 | 0.272659 | 0.580616 | 0.736016 | 1 |
Low pulse duration | 0.00 | 1.00 | 0.91 | 1.00 | 1.00 | 0.41 | 0.00 | 0.09 | 0.56 | 0.61 | 0.75 | 1.00 |
High pulse count | 0.00 | 1.00 | 1.00 | 1.00 | 1.00 | 0.29 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 0.44 |
High pulse duration | 0.00 | 1.00 | 1.00 | 1.00 | 1.00 | 0.46 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 4.56 |
Low Pulse Threshold | 0.70 | 0.57 | 0.53 | 0.56 | 0.59 | 0.45 | 0.01 | 0.05 | 0.14 | 0.25 | 0.34 | 1.00 |
High Pulse Threshold | 0.70 | 0.96 | 0.95 | 0.96 | 0.96 | 0.52 | 0.79 | 0.85 | 0.89 | 0.92 | 0.93 | 0.88 |
Group #5 | ||||||||||||
Rise rate | 0.70 | 1.00 | 0.99 | 1.00 | 1.00 | 0.67 | 0.91 | 0.93 | 0.96 | 0.97 | 0.98 | 0.86 |
Fall rate | 0.70 | 1.00 | 0.99 | 1.00 | 1.00 | 0.63 | 0.90 | 0.92 | 0.94 | 0.95 | 0.97 | 0.68 |
Number of reversals | 0.00 | 1.00 | 1.00 | 1.00 | 1.00 | 0.08 | 0.44 | 0.53 | 0.69 | 0.86 | 0.94 | 0.87 |
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Method Category | Resolution Level | Ecosystem | Time | Cost |
---|---|---|---|---|
Hydrologic | Very Low/Low | River | Short | Less |
Hydraulic rating | Low | River | Short/Long | Less/Medium |
Habit simulation | Medium/High | River | Medium/Long | Medium/High |
Holistic | High | Wetland, floodplains, | Long | High |
Name | Details |
---|---|
Elevation | 190 m to 8168 m |
Total catchment area | 11.851 km2 |
Location | 82°52.8′ E to 84°26.3′ E, 27°43.2′ N to 29°19.8′ N |
Mean annual precipitation | 1396 mm |
Flow data Series | 1 January 1964–31 December 2015 |
Min flow (m3/s) | 46 |
Mean flow (m3/s) | 449.7 |
Max flow (m3/s) | 6840 |
Min average monthly flow (m3/s) 10% of min average monthly flow (m3/s) | 90 9 |
EMC | Most likely Ecological Condition | Management Perspective |
---|---|---|
A (Natural) | Same as natural rivers with insignificant modification of instream and riparian habitat | Protected rivers and basins. Reserves and national parks. No new water projects (dams, diversions, etc.) allowed. |
B (Slightly modified) | Largely intact biodiversity and habitats despite anthropogenic activities (dam, diversion, basin modifications) | Water supply schemes or irrigation development present and/or allowed. |
C (Moderately modified) | The biota’s habitats and movement have been impacted, but essential ecosystem functions are still unmodified; some sensitive species are vanished and/or reduced in extent; alien species survived. | Multiple disturbances (for instance, dams, diversions, habitat modification, and reduced water quality) related to the need for socio-economic development |
D (Largely modified) | Substantial changes in natural habitat, biota, and essential ecosystem functions have occurred; a lower than expected species richness; the much-lowered presence of intolerant species; alien species prevail. | Significant and precise visible disturbances (such as dams, diversions, transfers, habitat modification, and water quality degradation) associated with basin and water resources development |
E (Seriously modified) | Habitat diversity and availability have declined; species richness is strikingly lower than expected; only tolerant species remain; indigenous species can no longer breed; alien species have invaded the ecosystem. | High human population density and extensive water resources exploitation. This class is not suitable as a management goal. The management team should move to a higher class to restore the flow pattern of the river. |
F (Critically modified) | Modifications have reached a tipping point; the ecosystem has been completely modified with an almost complete loss of natural habitat and biota; in the worst case, the underlying ecosystem functions have been destroyed, and changes are irreversible. | This status is not acceptable from the management perspective. Management interventions are necessary to restore flow patterns and river habitats (if still possible/feasible) to ‘move’ a river to a higher management category. |
Aquatic-Habitat Condition for Small Stream | Recommended Base Flow (% of MAF) | |
---|---|---|
General Period (October–March) | Fish Spawning Period (April–September) | |
Flushing or maximum | 200% of the average flow | |
Optimum range | 60–100 | 60–100 |
Outstanding | 40 | 60 |
Excellent | 30 | 50 |
Good | 20 | 40 |
Fair or degrading | 10 | 30 |
Poor or minimum | 10 | 10 |
Severe degradation | <10% of average flow to zero flow |
Global Index for Each Group | IHA Parameters | Regime Characteristic (Specific Alteration) | Ecological Significance |
---|---|---|---|
Mean Monthly Flow Alteration Index (Imm) | Group 1: Mean value of each calendar month | Magnitude (increased variation) | Guaranteed favourable habitat conditions and flow regime (quantity, quality, and temperature) for aquatic and terrestrial organisms. Availability of food and cover for fur-bearing mammals. |
Magnitude and Duration of Extreme Flow Alteration Index (IMDE) | Group 2: Annual minima, 1, 3, 7, 30, 90 day means Annual maxima, 1,3,7,30,90 day means Number of zero-flow days Baseflow index: 7 day minimum flow/mean flow for the year | Magnitude and Duration (prolonged low flows; altered inundation duration; prolonged inundation) | Structuring of aquatic ecosystems by abiotic and biotic factors. The shaping of river channel morphology and physical habitat conditions. |
Timing of Extreme Flow Alteration Index (ITE) | Group 3: Julian date of each annual 1 day maximum Julian date of each annual 1 day minimum | Timing (oss of seasonal flow peaks) | Disrupt cues for fish: (spawning, egg hatching, migration) [54]. Evolution of the life history and behaviour mechanism of the aquatic organisms [48]. |
Frequency and Duration Alteration Index (IFD) | Group 4: No. of high pulses each year No. of low pulses each year Mean duration of high pulses within each year (days) Mean duration of low pulses within each year (days) | Frequency and Duration (flow stabilization) | Availability of floodplain habitats for aquatic organisms. Influences bedload transport, channel sediment textures, and duration of substrate disturbance (high pulses). Nutrient and organic matter exchanges between river and floodplain. |
Rate and Frequency Alteration Index (IRF) | Group 5: Means of all positive differences between consecutive daily values Means of all negative differences between consecutive daily values Reversals | Rate of change and Frequency (rapid changes in river stage; accelerated flood recession) | Wash out and stranding of aquatic species [55]. Failure of seedling establishment [56]. |
Range | 0.00–0.25 | 0.25–0.50 | 0.50–0.75 | 0.75–1.00 |
---|---|---|---|---|
Alteration | Low | Mild | Moderate | High |
Method | Classes | (%of MAF) | E-flows (m3/s) | |||||||||
GEFC | Class B | 47.8 | 214.46 | |||||||||
Class C | 32.8 | 147.16 | ||||||||||
Class D | 23.7 | 106.33 | ||||||||||
Class E | 18.6 | 83.45 | ||||||||||
Class F | 15.7 | 70.44 | ||||||||||
Tennant | Oct–Mar | 10 | 44.87 | |||||||||
Apr–Sept | 30 | 134.6 | ||||||||||
FDC | Q80% FDCA, | 49.04 | ||||||||||
Q85% FDCA, | 45.65 | |||||||||||
Q90% FDCA, | 43.05 | |||||||||||
Mean annual flow | 10%MAF | 44.97 | ||||||||||
Dynamic methods | 30%Q-D | 30% of daily flow | ||||||||||
Annual Distribution Method | ||||||||||||
Month | Jan | Feb | March | April | May | June | July | August | Sep | Oct | Nov | Dec |
E-flow (m3/s) | 60.57 | 50.05 | 45.07 | 49.75 | 73.54 | 204.58 | 646.33 | 785.59 | 584.67 | 274.83 | 127.61 | 83.71 |
E-Flows Components (EFC) | Dynamic E-Flows | Minimum Annual | FDC Curve | ADM | Global Environmental Flow Calculator | Tennant | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
EFC Low Flows | 30%Q-D | 10%MAF | Q80% | Q85% | Q90% | Class B | Class C | Class D | Class E | Class F | ||
July—Low Flow | −70 | −100 | −100 | −100 | −100 | −46 | −100 | −100 | −100 | −100 | −100 | −70 |
August—Low Flow | −70 | −100 | −100 | −100 | −100 | −65 | −100 | −100 | −100 | −100 | −100 | −61 |
September—Low Flow | −70 | −100 | −100 | −100 | −100 | −35 | −100 | −100 | −100 | −100 | −100 | −72 |
October—Low Flow | −70 | −100 | −100 | −100 | −100 | −40 | −100 | −100 | −100 | −100 | −100 | −64 |
November—Low Flow | −70 | −100 | −100 | −100 | −100 | −49 | −100 | −100 | −100 | −100 | −100 | −41 |
December—Low Flow | −70 | −100 | −100 | −100 | −100 | −49 | −100 | −100 | −100 | −100 | −100 | −100 |
January—Low Flow | −70 | −100 | −100 | −100 | −100 | −48 | −100 | −100 | −100 | −100 | −100 | −100 |
February—Low Flow | −70 | −100 | −100 | −100 | −100 | −49 | −100 | −100 | −100 | −100 | −100 | −100 |
March—Low Flow | −70 | −100 | −100 | −100 | −100 | −50 | −100 | −100 | −100 | −100 | −100 | −100 |
April—Low Flow | −70 | −100 | −100 | −100 | −100 | −48 | −100 | −100 | −100 | −100 | −100 | −6 |
May—Low Flow | −70 | −100 | −100 | −100 | −100 | −34 | −100 | −100 | −100 | −100 | −100 | −15 |
June—Low Flow | −70 | −100 | −100 | −100 | −100 | −31 | −100 | −100 | −100 | −100 | −100 | −52 |
EFC Parameters | ||||||||||||
Extreme low peak | −70 | −100 | −100 | −100 | −100 | −41 | −100 | −100 | −100 | −100 | −100 | −39 |
Extreme low duration | 0 | −100 | −100 | −100 | −100 | −55 | −100 | −100 | −100 | −100 | −100 | 1393 |
Extreme low timing | 0 | −100 | −100 | −100 | −100 | −3 | −100 | −100 | −100 | −100 | −100 | 234 |
Extreme low freq. | 0 | −100 | −100 | −100 | −100 | 82% | −100 | −100 | −100 | −100 | −100 | −74 |
High flow peak | −70 | −100 | −100 | −100 | −100 | −62 | −100 | −100 | −100 | −100 | −100 | −100 |
High flow duration | 0 | −100 | −100 | −100 | −100 | −30 | −100 | −100 | −100 | −100 | −100 | −100 |
High flow timing | 0 | −100 | −100 | −100 | −100 | 26 | −100 | −100 | −100 | −100 | −100 | −100 |
High flow frequency | 0 | −100 | −100 | −100 | −100 | −2 | −100 | −100 | −100 | −100 | −100 | −100 |
High flow rise rate | −70 | −100 | −100 | −100 | −100 | −74 | −100 | −100 | −100 | −100 | −100 | −100 |
High flow fall rate | −70 | −100 | −100 | −100 | −100 | −81 | −100 | −100 | −100 | −100 | −100 | −100 |
Small Flood peak | −70 | −100 | −100 | −100 | −100 | −68 | −100 | −100 | −100 | −100 | −100 | −100 |
Small Flood duration | 0 | −100 | −100 | −100 | −100 | 11 | −100 | −100 | −100 | −100 | −100 | −100 |
Small Flood timing | 0 | −100 | −100 | −100 | −100 | 6 | −100 | −100 | −100 | −100 | −100 | −100 |
Small Flood frequency | 0 | −100 | −100 | −100 | −100 | −64 | −100 | −100 | −100 | −100 | −100 | −100 |
Small Flood rise rate | −70 | −100 | −100 | −100 | −100 | −96 | −100 | −100 | −100 | −100 | −100 | −100 |
Small Flood fall rate | −70 | −100 | −100 | −100 | −100 | −85 | −100 | −100 | −100 | −100 | −100 | −100 |
Large flood peak | −70 | −100 | −100 | −100 | −100 | −74 | −100 | −100 | −100 | −100 | −100 | −100 |
Large flood duration | 0 | −100 | −100 | −100 | −100 | −18 | −100 | −100 | −100 | −100 | −100 | −100 |
Large flood timing | 0 | −100 | −100 | −100 | −100 | −2 | −100 | −100 | −100 | −100 | −100 | −100 |
Large flood frequency | 0 | −100 | −100 | −100 | −100 | 260 | −100 | −100 | −100 | −100 | −100 | −100 |
Large flood rise rate | −70 | −100 | −100 | −100 | −100 | −88 | −100 | −100 | −100 | −100 | −100 | −100 |
Large flood fall rate | −70 | −100 | −100 | −100 | −100 | −71 | −100 | −100 | −100 | −100 | −100 | −100 |
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Suwal, N.; Kuriqi, A.; Huang, X.; Delgado, J.; Młyński, D.; Walega, A. Environmental Flows Assessment in Nepal: The Case of Kaligandaki River. Sustainability 2020, 12, 8766. https://doi.org/10.3390/su12218766
Suwal N, Kuriqi A, Huang X, Delgado J, Młyński D, Walega A. Environmental Flows Assessment in Nepal: The Case of Kaligandaki River. Sustainability. 2020; 12(21):8766. https://doi.org/10.3390/su12218766
Chicago/Turabian StyleSuwal, Naresh, Alban Kuriqi, Xianfeng Huang, João Delgado, Dariusz Młyński, and Andrzej Walega. 2020. "Environmental Flows Assessment in Nepal: The Case of Kaligandaki River" Sustainability 12, no. 21: 8766. https://doi.org/10.3390/su12218766