Figure 2.
Combination of spatial and temporal scales in Mahaweli Basin water management.
4.2. Water-Climate-Energy-Food Nexus in Competing Interests of Scale (Re) Configuration
The Master Plan for the MDP was assessed in 1965–1968 by the United Nations Development Program (UNDP), the Food and Agriculture Organization (FAO) team, and Sri Lankan engineers [
50,
51]. The program was implemented in 1970 and then restarted in 1977 under the new government. Hydropower generation and agricultural development could be observed as the main political objectives that motivated the MDP. Water allocation and distribution are based on the competitive interests of stakeholders in the MDP. The demand for water resources is shared among macro and micro hydro-electrical plants, vegetable farmers upstream (mainly in the highland of Sri Lanka), paddy farmers downstream, and industries. Through an analysis of the temporal locus of the development paradigm, it could be observed that the locus and focus of the MDP have been changing. As a result of state-oriented development programs after independence in 1947, large-scale and multi-purpose water resource management programs were politically manifested. The state-led development before the 1980s was mainly motivated by promoting welfare programs and land reform for peasant farmers, allocating lands for agriculture in semi-arid dry zone areas with relatively low population density, and promoting paddy cultivation in the national economy [
52,
53].
To promote paddy cultivation in the national economy, new paddy fields were constructed in Mahaweli Basin irrigation regions and then were distributed among new settlers. The downstream area of the Mahaweli River Basin has been demarcated into 13 irrigation regions (
Figure 1). Each region has been divided into sub-regions from 1000 hectares to 1500 hectares in land area [
54]. Furthermore, these sub-regions have been partitioned into hamlets (village units) of 150 families [
55]. The aim of the divisions is a manageable irrigation region and functional human settlement system [
54,
55]. According to new information in 2012, there are 365,000 cultivated hectares in the Mahaweli River Basin area, including 10,049 km of canal networks [
48]. Currently, approximately 2.8 million people live in the Mahaweli River basin, which is about 15% of the population of Sri Lanka [
7]. There are about 166,269 households in the Mahaweli settlement areas [
50]. Most settlers migrated from the central parts or western hill slopes of Sri Lanka as landless peasants [
56]. They settled under the government program in the Mahaweli irrigated regions (Mahaweli Irrigation Systems/Zones) from A to M (
Figure 1). Each household was permitted 1 hectare of irrigated lowland for paddy cultivation and 0.2 hectares of rain-fed highland farm steading [
56]. The spatial responsibilities of the Mahaweli Authority extend beyond the physical context of the Mahaweli River Basin. Chiefly, the Udawala project in the Walawe River Basin in southern Sri Lanka and some irrigational regions including H, I, L, and M are located beyond the physical context of the Mahaweli River Basin (
Figure 1). Furthermore, the irrigation regions M and M/H are located in the Yan Oya basin. These sub-river basins are connected by water diversion from the Mahaweli River. As discussed, water diversion between sub-river basins is another purpose of the MDP.
In contrast, neoliberal political transformation was the driving force of state policies after the 1980s. Within this context, the government acts as a facilitator to construct infrastructure facilities for the private sector in the context of a market economy [
53]. This created vital changes in the focus of the MDP by facilitating electricity generation for the Free Trade Zones. From the 1980s onwards, the priority of the MDP shifted to establishing hydropower plants by constructing large dams upstream and in the middle reach of the Mahaweli River [
52,
57]. Large dam constructions are the expression of a modernization path following a Western technologic-economic rationality. Large, multi-purpose dams are the center of the hegemonic hydraulic paradigm [
58], and their planning and implementation have often disregarded concerns for social and environmental sustainability. In the case of the MDP, major foreign investments have been allocated to constructing water reservoirs as the basis of hydropower generation, such as the Kotmale, Victoria Randenigala, Rantembe, Ulhitiya/Ratkinda Madu Oya Maduru Oya, Bowetenna, Udawalawe, Ukuwela, and Polgolla hydropower plants. Meanwhile, the MDP is being expanded to new spatial areas beyond the physical context of the Mahaweli River Basin, to include such ventures as the Moragahakanda and Kaluganga Rivers Development Projects, the Rambaken Oya Development Project, and the Kiwul Oya Reservoir Development Projects [
50]. Under the Moragahakanda-Kaluganga Project in 2007, the government expects to enhance hydropower generation as well as drinking water purposes and cropping intensity in the Mahaweli River Basin settlement areas [
50]. In 2005, 30% of national hydropower production was from the hydropower plants within the Mahaweli system [
36].By contrast, 49% of national hydropower was generated under the MDP in 2011. The total power generation to the national grid from the Mahaweli system is 1975 Gigawatt hours (GWh), which is 49% of the total hydro power in Sri Lanka [
50].
The gradual socioeconomic transformation from an agriculture-oriented society into a more industrial-oriented society [
37] may place high demands on water resources in the MDP. The statistical analysis of the sectoral water withdrawal in Sri Lanka demonstrates the increase of industrial water use and domestic water use, and the gradual decrease of agricultural water demand. As
Figure 4 shows, the irrigational usage of water has gradually declined. It is estimated that irrigational water usage in 2025 will be between 70% and 75%. However, other competing sectoral water demands challenge the demand for water in paddy cultivation. According to this trend, water usage for domestic purposes and industries are expected to gradually increase. FAO-AQUASTAT data on renewable internal freshwater resources per capita per year (actual) in Sri Lanka indicates 2482 m
3 in 2014 [
59], which shifts the country into the vulnerable category (based on UN WWDR and UN-Water category thresholds [
60]) compared to 2012 data. Under the conditions of high-demand water consumption and a challenging climate, the water-climate-energy-food nexus is being contested by the changing economic interests and political manifestations of natural resource management at the national level. At this juncture, MDP can be observed as a core realm of competing interests over water resources integrating local socio-economic demands at the regional level.
Figure 4.
Sectoral Water Demand in Sri Lanka from 1990 to 2025. (Source: The Annual Report—Economic perspective Sri Lanka [
39]).
Figure 4.
Sectoral Water Demand in Sri Lanka from 1990 to 2025. (Source: The Annual Report—Economic perspective Sri Lanka [
39]).
4.3. Impacts of Seasonal and Temporal Climate Change on Paddy Cultivation
Temporal and spatial changes in climate conditions and weather systems are crucial factors to take into consideration in the dry zonal water resource management. Releasing water for paddy cultivation depends on the flow regimes of the Mahaweli River and its tributaries. There are two trends reflecting seasonal flow regimes, including the impact of high precipitation and the gradually declining precipitation in catchment areas. As a result of spatial and temporal variations in climate conditions, specifically declining precipitation, rising air and soil temperature, and increasing evaporation rates in the irrigational management areas of the Mahaweli River Basin, alteration of seasonal-oriented agricultural decisions in the field study areas could be observed.
There are two main seasons of paddy cultivation in the dry zone,
maha (October to February/March) and
yala (March/April to July/August) which are defined on the basis of periodic precipitation. Based on the field data, the average precipitation in the
maha season could be ranged 750 mm to 1000 mm, and average precipitation in the
yala season could be around 500 mm or less. In the dry zone, the
maha season is the main harvesting season. Some farmers cultivate other crops (grains or vegetables) during the
yala and
maha seasons, called intermediate cultivation. However, the decision to cultivate an intermediate season depends on water availability. Though agriculture in the dry zone is mainly based on irrigated water, some farmers are accustomed to using rain-fed water in the
maha season and irrigated water in the
yala season based on seasonal variation of precipitation. Water allocation and distribution for paddy cultivation under the MDP also operate based on this general assumption. However, this seasonal-oriented paddy cultivation is challenged by the impacts of long-term climate change and uncertainty in weather systems. Eriyagama
et al. [
37] estimate that the water requirement for paddy cultivation in the
maha season would be 13%–23% in 2050, as compared to the period from 1961–1990 with reference to quantity and spatial distribution of precipitation and changes in mean temperature.
Figure 5.
Losses to agricultural crops in hectares due to droughts and floods, 1974–2007. (Source: Sri Lanka National Report on Disaster Risk, Poverty, and Human Development Relationship, the Disaster Management Centre (DMC) of Sri Lanka [
49]).
Figure 5.
Losses to agricultural crops in hectares due to droughts and floods, 1974–2007. (Source: Sri Lanka National Report on Disaster Risk, Poverty, and Human Development Relationship, the Disaster Management Centre (DMC) of Sri Lanka [
49]).
The frequent occurrence of dry weather conditions in recent years has resulted in declining overall agricultural output in downstream areas [
61,
62,
63]. Particularly, paddy cultivation in the dry zonal area exposes it to short-term and extended severe drought conditions. Paddy yields at early stages of the agronomic period have been affected due to short-term droughts. Furthermore, the lack of water distribution in the reproductive phase of rice could reduce the harvest of paddy. Because of that, farmers are unable to achieve off-season harvesting and intermediate cultivation due to declining rainfall in the
yala season. According to data from the Disaster Management Centre of Sri Lanka (DMC) [
49], severe drought conditions brought about damage to agricultural land, particularly in the dry zone area. In the period from 2001 to 2004, the dry zone area was exposed to extended drought conditions in both the
yala and
maha periods. In the range of the research area, Hambanthota and Kurunegala are the other districts that were affected by these drought conditions.
Figure 5 illustrates the losses of agricultural crops in hectares caused by droughts within the period of 1974 to 2007 [
49]. The size of fields under paddy cultivation has been reduced to 66,194 hectares in the dry and intermediate zones of the Mahaweli River Basin as a result of severe drought conditions in the
yala season in 2012 [
48]. Based on the field data, the dry zone is again prone to be exposed to extended drought conditions from
maha season in 2013 to
yala season in 2014. These drought conditions impact paddy cultivation as well as the cultivation of other crops. The exact losses to agriculture caused by drought conditions have not yet been officially calculated. Based on the Sri Lanka Disaster Management Center’s data from 1974 to 2008 on the frequency and scale of disasters, the Sri Lankan Ministry of Environment analyzes the spatial distribution of extended drought conditions that create vulnerability in the irrigation sector [
5] (
Figure 6). Based on this GIS-based analysis at the divisional secretariat (DS) level, the high level of vulnerability in the irrigation sector can be scrutinized in the Mahaweli D2, H, I/H, M/H, I, J, L, and M regions.
The interview data explains that paddy cultivation especially in the
yala season was either abandoned or earned a limited harvest throughout the last 10-year period. According to the farmers’ experiences, there is latent competition over water allocation during periods of limited water availability. According to the authorities of the MDP, water supply for paddy cultivation is frequently controlled and limited due to the inadequate water availability in water tanks and tributaries that are located in the Mahaweli River basin [
64]. In interviews, paddy farmers repeatedly expressed deep concern over the lack of adequate water resources, especially during the
yala season. The latest data demonstrate that in the
yala season of 2014, about 35,000 acres in the Polonnaruwa District (MDP regions) could not be cultivated because of drought conditions [
64].
Most of Mahaweli irrigation regions are affected by drought, and the situation has a reciprocal influence on current water resource management practices. The recent drought conditions are extending to Mahaweli B, C, H, and G regions including the Polonnaruwa, Girandurukotte, Galewela, Dambulla, Dehiattakandiya, Anuradhapura, Elahera, Tambuettegama, and Kandalama divisional secretariats (DS) [
64]. At the field level, the spatial expansion of dry zonal conditions could be observed towards the intermediate climate zone, which points to the vulnerability of farmers in Kurunegala and Matale districts.
Figure 7 demonstrates the impact of drought conditions on paddy cultivation at the divisional secretariat level [
5]. According to this GIS-based explanation, a high level of vulnerability in the paddy sector can be observed in the Mahaweli H, I/H, M/H, I, and J regions, as well as the Horrowpothana divisional secretariat. Farmers reveal that they have encountered extensive losses of their paddy harvest over the last 10 years due to increased air temperature and extended drought periods in the
maha and
yala harvesting periods. Consequently, these effects induce an increase in surface temperature [
33,
65], which causes deterioration of harvest in paddy cultivation [
66]. According to Matthews
et al. [
67], the increase of seasonal average temperature reduces the paddy harvest. Welch
et al. [
68] state that a higher minimum temperature decreases the paddy yield, while a higher maximum temperature could increase paddy cultivation. The evaporation of water from rivers and water tanks, diminishing soil moisture, and declining groundwater recharge affect paddy cultivation under the drought conditions [
5].
Figure 6.
Irrigation sector vulnerability to drought exposure.
Figure 6.
Irrigation sector vulnerability to drought exposure.
DS: Divisional Secretariat. (Map is re-illustrated based on the data from the Climate Change Vulnerability Data Book [
5].)
Constant stream flow cannot be expected throughout the year in the Mahaweli River. Heavy rainfall in the upper catchments, activation of inter-monsoon rainfall in the dry zone area, and cyclone condition activation in the Bay of Bengal generate high stream flow in the river, tributaries, and water channels. These temporal changes in climate conditions and weather systems impact the seasonal orientation of paddy cultivation. Observation demonstrates that farmers are highly vulnerable to unexpected flooding in the
yala and
maha seasons. Their anxiety over crop protection from flooding of the farm fields is a major issue in agriculture. For example, the activation of the Northeast monsoon in the month of December 2010 severely damaged small, medium, and even large-scale irrigation projects. The DMC data [
49] shows considerable damage to agricultural lands because of flood conditions from 1974 to 2008. In the dry zonal area, the Polonnaruwa, Batticaloa, Killinochchi, and Ampara districts encountered severe flood conditions over the last 34 years. As illustrated in
Figure 5, substantial losses to agricultural lands (paddy and other crops) were documented in 1978, 1984, 1986, and the period from 1999 to 2008. Around 303,957 hectares of paddy were critically damaged due to drought conditions between 1974 and 2007 [
69]. As the Central Bank report of Sri Lanka [
63] states, the canal network and 67,900 hectares of agricultural land were submerged and 6285 hectares were destroyed. Most of these irrigated projects and agricultural lands are located in the A, B, and D irrigation regions of the MDP [
63]. Due to the uncertainty in weather conditions and climate change scenarios, the seasonal dynamics of flow regimes have to be considered with regards to water productivity in agriculture. Seasonal dynamics of river flow regimes should be carefully assessed and studied, because variation of water quantity in rivers and tributaries impacts hydropower generation, irrigation, flood risk management, and water allocation, which are all components of a holistic river basin-oriented water management plan.
Figure 7.
Paddy sector vulnerability to drought exposure.
Figure 7.
Paddy sector vulnerability to drought exposure.
DS: Divisional Secretariat. (Map is re-illustrated based on the data from the Climate Change Vulnerability Data Book [
5].)
Drought and floods cause depleted yields or harvest failure, which leads to socioeconomic hardship for small-scale farmers. As recorded from 1974 to 2007 (
Figure 8), major hazards that adversely affected paddy cultivation are drought conditions (around 50.83%) and flood conditions (around 45.83%). In total, 578,014 hectares under paddy cultivation have been severely damaged due to flood and drought in the 1974–2007 period [
69]. Farmers were concerned not only about limited water availability, but also about local, small-scale irrigation technologies, which are in a state of disrepair. With regards to the role of MDP authorities and other state agencies, farmers complained about the irrigation bureaucracy’s failure to adequately meet their preferences in water allocation, and its lack of attention on maintenance and operation of water supply systems. Therefore, spatial and temporal impacts of climate change and climate variability with drought and flood conditions could reshuffle or alter seasonal decisions on agricultural practices.
Figure 8.
Effect of hazards on paddy cultivation, 1974–2007.
Figure 8.
Effect of hazards on paddy cultivation, 1974–2007.
* Others: cyclone, gale, landslide, plague, frost, tsunami, forest fire, and storm (Source: Sri Lanka Disaster Knowledge Network [
69]).
4.4. Modern and Traditional Application in Irrigational Water Management
Historical evidence demonstrates that water resources and riparian areas of the Mahaweli River had been used for water diversion through canalling and construction of the cascade system for agriculture and domestic consumption [
70,
71,
72]. The traditional irrigation system, which was based on the strong hydraulic civilization of about 2000 years ago (around 250 B.C. to around 1100 A.D.) in the dry zonal area, is considered an appropriate system for dealing with harsh, changing climate conditions and has the capacity of adapting to long-term changes in climate [
72,
73]. However, a discrepancy between modern application in the MDP and traditional knowledge of irrigational water management has been observed.
With the development of the agriculture and irrigation sector in the MDP, a considerable number of village tanks (
kotu wewa), which were common in the dry zone, were converted into paddy fields. These new paddy fields were distributed among new settlers. The purpose of the village tanks was to supply water for agriculture and other human purposes during extended dry seasons. These small tanks were used when the water level decreased in other, major tanks. The village tank (
kotu wewa) system is considered the oldest tank system in Sri Lanka [
73]. In ancient times settlements in the dry zone were located around a tank (
wewa) rather than along or near a water channel in the dry zone area. The village tanks (
kotu wewa) were also an essential unit of the traditional river-basin-oriented complex water management system. The tanks were stored with rainwater or the diverted water from a channel barricaded by small anicut (dams). C. M Madduma Bandara conceptualizes this system as a cascade system which is defined as a “connected series of tanks organized within a micro-catchment of the dry zone landscape, storing, conveying and utilizing water from ephemeral rivulets” ([
71], p14). A cascade of tanks is constructed by 4 to 10 individual small tanks, with each tank having its own micro-catchment. All village tanks were situated within a single meso-catchment basin that was organized in extent from 15.5 km
2 to 25.8 km
2, with a model value of 20.7 km
2 in the dry zone area. The outflow from a tank was stored by a downstream tank. This water storage could be applied within the command area of the second tank. Thus, the channel runoff was continuously recycled and refilled. This system could assist to surmount the problems of irregularly distributed rainfall, non-availability of large catchment areas, and the difficulty of large tank construction [
73]. Local people and archeologists assume that these village-based small tanks have been constructed based on long-term experience of climate conditions and changes in the dry zone area. However, few village tanks (
kotu wewa) are still operated for water allocation and distribution in paddy cultivation and other human purposes at the village level in the dry zone area.
Some of the old water channel systems were also reconstructed in concrete under the MDP. In the Eppawal division,
Yoda Ela (a water diversion channel), which flowed by nurturing the ecosystem and recharging the groundwater, is reconstructed with concrete as
Nawa Jaya Ganga. However, the expected goals from this reconstruction cannot be achieved because the water channels are inundated in the inter-monsoon period [
74]. A considerable portion of the paddy harvest is destroyed every year due to unexpected flooding conditions in the Eppawala division. Mishandling or ignorance of traditional technology in water distribution also leads to diminishing soil moisture and impacts on the paddy fields and water springs as a result of lack of recharge of groundwater.
The complex irrigational management system in the MDP weakens voluntary engagement of farmers in water resource management (
Figure 9). This complexity leads to the strengthening of bureaucrats in irrigation and agricultural management [
75,
76,
77]. Due to this hydrocracy [
78] in water resource management in the MDP, societal demands and ecological changes are disregarded under bureaucratic control of the technical infrastructure. The highly centralized administrative and management system in the MDP hinders voluntary farmer involvement [
76,
77,
79]. Water allocation and distribution is mainly administered by the officers in the regional office of the Mahaweli Authority in each irrigation region. The research data demonstrate that the “
kanna rasweema” (the meeting at the cultivation period) in most regions in the Kantale and Horrowpothana divisions do not empower farmers’ voluntary decision-making. At the village level, “
kanna rasweema” is a participatory body of farmers competent in decision-making regarding water allocation and distribution. Though farmer associations are responsible for the operation and maintenance of small and minor irrigation schemes, officers in the regional office of the Mahaweli Authority supervise and operate water management. The miscommunication or ignorance of farmers’ water demands is the main reason for the loss of expected profit from paddy cultivation prior to other factors, such as pricing issues or lack of storage.
The lack of participation of the farmer associations in water allocation and distribution currently leads to the malfunction of the irrigation canal system at the micro level. The spatial changes in the dry zone are not identified in order to reorganize the water allocation system. The farmers’ experience and traditional knowledge are rarely acknowledged or taken into consideration within the water resource management planning of the MDP. Within the technocratic irrigational system of the MDP, farmers are either discouraged or prevented from accessing traditional applications in water resource management such as diya bäduma. The term diya bäduma refers to the gradual water allocation system from main water flow (the river) by barricading small anicut (dams). The diverted water flows into the small canal, then into a water channel in a farm field. In the diya bäduma system, the direct engagement of villagers is a crucial factor because the amount of water diversion, time period, and area of spreading water are decided upon the voluntary participation and will of the people. Traditional irrigational practices are considered as part of the traditional body of knowledge adapted to changing climate conditions, ecosystem, and social demands. Lack of opportunities for voluntary engagement in water resource management, especially canal management and water allocation and distribution, contribute to the malfunction of the irrigation canal system at the micro level.
Figure 9.
River basin-oriented management system and political-administrative management system in the Mahaweli River Basin area (authors’ analysis).
Figure 9.
River basin-oriented management system and political-administrative management system in the Mahaweli River Basin area (authors’ analysis).
(Arrows indicate the flow of responsibilities and administrative power)