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- Title
Water availability assessment in cultivation and non-cultivation seasons to identify water security in a tropical catchment: Gin catchment, Sri Lanka.
- Authors
Wickramaarachchi, T. N.
- Abstract
Human activities and extreme hydrological events are posing continuing threats to sustainable management of water resources in Gin catchment, Sri Lanka (972 km2), a rain-fed agriculture-dominated catchment in the tropics which experiences uneven temporal rainfall distribution. This study aims to assess the seasonal water availability in the Gin catchment by setting up of Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) rainfall–runoff model. The HEC-HMS continuous-based simulation performed well with Nash–Sutcliffe efficiency, NSE ≥ 0.72 and percent bias, PBIAS ≤ − 6.8% during the calibration (2011–2014) and validation (2015–2017). The seasonal and annual water balance volumes during 2011–2017 were simulated reasonably well with 10–13% error and 3% error on average, respectively. The modeling results indicated clear seasonal variation with respect to the availability of water depicting 64% of the annual water yield generation in the cultivation seasons, Yala (April–June) and Maha (October–December), dominated by the monsoon rains. The direct surface runoff regime has become the dominant component in the two cultivation seasons (68–70%), and the precipitation loss volume constituted higher percentage in the non-cultivation season (44%) in comparison with the cultivation seasons (28%). Even during the non-cultivation season which coincides with the dry months of the year (January–March and July–September), a significant contribution of baseflow to the total streamflow (40%) was evident which will favorably impact the rain-fed perennial crops. Maintaining the environmental flow requirement, Q90 (≈ 18 m3/s), in the river during the driest month (March) should be given attention in the proposed Gin–Nilwala inter-basin diversion plan in the upstream catchment.
- Subjects
SRI Lanka; WATERSHEDS; WATER supply; WATER management; GIN; SEASONS; RAINFALL
- Publication
Paddy & Water Environment, 2024, Vol 22, Issue 1, p85
- ISSN
1611-2490
- Publication type
Article
- DOI
10.1007/s10333-023-00954-6