Otto J. Helweg

Problems with Traditional Small Reservoir Irrigation Systems in the Semi Arid Tropics

ABSTRACT traditional method of irrigating in the semi-arid tropics (especially India) is collecting monsoon precipitation in small reservoirs, called tanks, to supply irrigation water for the dry season. Though there is considerable investment being proposed to develop more tank irrigation systems and improve those that already exist, there have been no studies evaluating their design and operation efficiency. This project studied two of these systems in detail to compare their potential overall water utilization efficiency (WUE) with their actual WUE. The results showed that the overall system WUEs were three to five times lower than their potential WUE. This was caused by poor system design, improper system maintenance, and inefficient irrigation practices. The authors suggest some practical methods to improve these traditional tank irrigation systems that may be applicable in similar areas of the world.

Nonlinear Reservoir Analysis with Risk-Benefit Objectives

ABSTRACT The surrogate worth trade-off method has been extended to a quadratic programming optimization model and risk has been incorporated into the vector of objective functions which explicitly shows the decision maker the trade-offs between net benefits and increased reliability of the system or the trade-offs between competing reliabilities such as flood control and water supply. The approach is called the Nonlinear Risk-Benefit (NRB) Algorithm. The NRB Algorithm is applied to the Broken Bow Reservoir to illustrate the increased information made available by this approach.