Dynamical variations in groundwater chemistry influenced by intermittent water delivery at the lower reaches of the Tarim River

The water of Bosten Lake was released to lower reaches of the Tarim River for 5 times from 2000 to 2002. The changes of total dissolved solid (TDS) and the major ions (SO2-4, Cl-, Na+, Ca2+, Mg2+ and HCO-3) were analyzed during this period. It was found out that TDS and the concentrations of the major ions initially and quickly increased and then decreased, but finally increased again. These changes were different at different distances from the river, which indicated that the groundwater changes relied on the distance from the river. In addition, the salt in groundwater was only diluted but not removed by the water. It was suggested that ecological measures should be sought to really promote the quality of the groundwater at the lower reaches of the Tarim River.

Evaluation of Water Delivery Performance of Nkhafi Irrigation Scheme in Dowa District, Malawi, Africa

This study evaluated the water delivery performance of Nkhafi irrigation scheme based on adequacy, water delivery efficiency, equity, dependability and irrigation efficiency. Primary data were collected from field measurements, scheduled interviews, group discussions and use of a structured questionnaire. CROPWAT 8.0 computer model was used to determine crop water requirements and irrigation requirements. The results revealed that adequacy, water delivery efficiency, equity, dependability and overall water delivery performance were (0.74;0.82), (0.70;0.80), (0.15;0.20), (0.11;0.21) and (0.80;0.80) for 2017 and 2018 seasons respectively. The scheme overall irrigation efficiencies were 20% and 25% for 2017 and 2018 respectively. These findings revealed that scheme users failed to deliver adequate and dependable water in an effective manner in both growing seasons. This occurred due to insufficient water supply, poor irrigation scheduling, lack of adequate knowledge and skills in operating and rehabilitating hydraulic structures, siltation and water losses through seepage in canals. Therefore, it is recommended that major maintenance works need to be done along the whole canal network in order to achieve good overall water delivery performance. Furthermore, farmers need to be trained in water management, sustainable agricultural production practices, operation and maintenance of irrigation structures. The study has provided an insight on the status of the scheme hence encouraging scheme users to improve water delivery performance.

Water-conserving Potential for Agriculture in the Tarim Basin

o satisfy the water demand for Tarim Basin's economic development in the year 2000, about 33 4×10 8 m 3 water needs to be further tapped. According to the analysis of the current status of water utilization, it is pointed out that, to achieve such economic objectives, the policy of emphasizing both water exploitation and water conservation with the preference given to conservation measures must be followed. For this end, the potentials of exploring new additional sources and strengthening water conservation have been well analyzed, along with the calculation and tech economic assessment of some related parameters like the canal transmission efficiency in water delivery systems and the water irrigation efficiency in the field. The results indicate the potentials of water resource expansion and conservation are 34×10 8 m 3 and 57×10 8 m 3, respectively. Based on such research outputs, a water conservation program has been developed for the Tarim Basin, to provide important references and policy recommendations for the decision makers in Xinjiang agricultural department to implement water utilization measures.