Evolution, present status and issues concerning small tank systems in Sri Lanka [Small tanks in Sri Lanka: evolution, present status and issues]

Tank irrigationHydrologyWater qualityIrrigation managementWater managementWater distributionWatershedsIrrigation designMaintenanceFarming systemsGovernmental interrelationsSmall scale systemsVillagesHistory

The small tank cascade systems of the Rajarata: Their setting, distribution patterns, and hydrography

Tank irrigation / Maps / Watersheds / River basins / Environment / History / Sri Lanka / Rajarata / Mahaweli Project / Kala Oya / Moderagam Ara / Malwathu Oya / Parangi Ara / Ma Oya / Mee Oya / Yan Oya / Koddikkaddi Ara / Pankulam Ara

Irrigation management for crop diversification in Sri Lanka: A synthesis in current research

Irrigation management / Crop yield / Diversification / Farmer-agency interactions / On-farm research / Water delivery / Water supply / Weirs / Communication / Sri Lanka / Dewahuwa / Kalankuttiya / Mahaweli Project

Irrigation and drainage in the new millennium

Presented at the 2000 USCID international conference, Challenges facing irrigation and drainage in the new millennium on June 20-24 in Fort Collins, Colorado.Includes bibliographical references.Climate potential in respect to onset, magnitude and risk associated with rainfall for crop production in the Nilwala basin, Southern Sri Lanka was assessed using the daily rainfall of 12 stations scattered in different locations for more than 35 consecutive years (1950-1995). The program CROPWAT was used to assess the irrigation need. It was revealed that rainfall of the basin increases from south to north with increasing elevation and altitude. Within a 70-km distance in the south north gradient, rainfall elevates from 1656 mm at Kekanadura to 4216 mm at Kudawa. The net irrigation requirement of Yala rice in different locations varied from 1012 mm to 1246 mm. It was established that the irrigation need in the Nilwala upper catchment is below 40 % of the total water requirement, but in downstream areas it constitutes above 70% of the total water demand. Therefore both the Yala and Maha seasons in Nilwala downstream areas appeared to be unsuitable for rice cultivation without supplementary irrigation. From April 10th onward until May 20th is the best period for establishment of perennial crops at upper catchment areas. Optimum dates for crop establishment at the mid and lower part of the catchment falls on the 14th meteorological week. It is important to note that delaying crop establishment in Yala by 2 or 3 weeks from the optimum date would result in a considerable increase of irrigation need even in the upper catchment areas; it is not advisable to delay the establishment of Maha rice until October when rice varieties off our month duration are cultivated

Pre-project technical assistance study for proposed Area Development Project of North Central Province

Tanks / Water resources / Surface water / Rain / Water availability / River basin development / Water balance / Case studies / Irrigation programs / Development projects / Water resources development / Sri Lanka / North Central Province / Mahaweli Project / Anuradhapura / Polonnaruwa

Nature of small tank cascade systems and a framework for rehabilitation of tanks within them

Tank irrigation / Water resource management / Irrigated farming / Small scale systems / Hydrology / Surface water / Groundwater / Rehabilitation / Sri Lanka / Anuradhapura

Seasonal planning procedures to improve irrigation management performance: How Kirindi Oya experience can be transferred to NIRP schemes. Proceedings of the Workshop on Seasonal Planning Procedures to Improve Irrigation Management Performance: How Kirindi Oya experience of IIMI/ID can be transferred to NIRP schemes, held at the Irrigation Department, Colombo, Sri Lanka, on 16 May 1994

Irrigation managementIrrigation systemsMaintenanceCropsDiversificationSettlementSalinityWater use efficiencyResource managementRehabilitationPerformance

Potential for diversified cropping in the rice lands of Sri Lanka

Irrigation management / Irrigated farming / Rice / Crops / Diversification / Crop production / Yield / Economic aspects / Costs / Farmer-agency interactions / Sri Lanka

Climate change and agricultural adaptation in Sri Lanka: a review

Climate change is inevitable and will continue into the next century. Since the agricultural sector in Sri Lanka is one of the most vulnerable to climate change, a thorough understanding of climate transition is critical for formulating effective adaptation strategies. This paper provides an overview of the status of climate change and adaptation in the agricultural sector in Sri Lanka. The review clearly indicates that climate change is taking place in Sri Lanka in terms of rainfall variability and an increase in climate extremes and warming. A number of planned and reactive adaptation responses stemming from policy and farm-level decisions are reported. These adaptation efforts were fragmented and lacked a coherent connection to the national development policies and strategies. Research efforts are needed to develop and identify adaptation approaches and practices that are feasible for smallholder farmers, particularly in the dry zone where paddy and other food crops are predominately cultivated. To achieve the envisaged growth in the agricultural sector, rigorous efforts are necessary to mainstream climate change adaptation into national development policies and ensure that they are implemented at national, regional and local levels

Impacts of the 2004 tsunami on groundwater resources in Sri Lanka, Water Resour

[1] The 26 December 2004 tsunami caused widespread destruction and contamination of coastal aquifers across southern Asia. Seawater filled domestic open dug wells and also entered the aquifers via direct infiltration during the first flooding waves and later as ponded seawater infiltrated through the permeable sands that are typical of coastal aquifers. In Sri Lanka alone, it is estimated that over 40,000 drinking water wells were either destroyed or contaminated. From February through September 2005, a team of United States, Sri Lankan, and Danish water resource scientists and engineers surveyed the coastal groundwater resources of Sri Lanka to develop an understanding of the impacts of the tsunami and to provide recommendations for the future of coastal water resources in south Asia. In the tsunami-affected areas, seawater was found to have infiltrated and mixed with fresh groundwater lenses as indicated by the elevated groundwater salinity levels. Seawater infiltrated through the shallow vadose zone as well as entered aquifers directly through flooded open wells. Our preliminary transport analysis demonstrates that the intruded seawater has vertically mixed in the aquifers because of both forced and free convection. Widespread pumping of wells to remove seawater was effective in some areas, but overpumping has led to upconing of the saltwater interface and rising salinity. We estimate that groundwater recharge from several monsoon seasons will reduce salinity of many sandy Sri Lankan coastal aquifers. However, the continued sustainability of these small and fragile aquifers for potable water will be difficult because of the rapid growth of human activities that results in more intensive groundwater pumping and increased pollution. Long-term sustainability of coastal aquifers is also impacted by the decrease in sand replenishment of the beaches due to sand mining and erosion