6533b81ffe1ef96bd1278480

RESEARCH PRODUCT

Economic Aspects of the Conjunctive Use of Ground and Surface Water

subject

description

Abstract The different structure of the costs of ground and surface water and the different and complementary characteristics of both kinds of resources make it possible to solve the specific needs of water quantity and quality more adequately and economically if both resources are used conjunctively. Higher discount rates favour the inclusion of elements involving lower initial investment and generally with higher groundwater components. Lower discount rates favour a higher participation of surface water. The external factors produced by groundwater pumping must be taken into consideration in any economic analysis. Examples of external factors are water level descents, surface water flow reduction, degradation of wetlands and ecological issues, water quality deterioration and land subsidence. This paper discusses the economics of artificial recharge and its role in the different types of conjunctive use. Its importance is crucial in some cases and secondary or marginal in others. The amount of stored ground water in many cases is several tens or hundreds of times the mean annual groundwater recharge level. Planned overpumping allows costly projects requiring large dams or transfer structures to be postponed. The uncertainty inherent in river flow prediction and demand variability or inadequate information of the hydrological parameters of the system can be counteracted by the flexibility in the seasonal and yearly use of ground water which conjunctive use schemes provides. In many cases this represents a kind of insurance against adverse hydrological or economic situations.