Estimation of Natural Groundwater Recharge

In view of the rapidly expanding urban, industrial and agri­ cultural water requirements in many areas and the normally associated critical unreliability of surface water supplies in arid and semi-arid zones, groundwater exploration and use is of fundamental importance for logical economic development. Two interrelated facets should be evident in all such groundwater projects : (a) definition of groundwater recharge mechanisms and characteristics for identified geological formations, in order to determine whether exploitation in the long-term involves 'mining' of an es­ sentially 'fossil' resource or withdrawal from a dynamic supply. A solution to this aspect is essential for development of a re­ source management policy: (b) determination of recharge variability in time and space to thus enable determination of total aquifer input and to quantify such practical aspects as 'minimum risk' waste disposal locations and artificial recharge potential via (e.g.) devegetation or engi­ neering works. However, current international developments relating to natural recharge indicate the following 'problems' ; no single comprehensive estimation technique can yet be iden­ tified from the spectrum of methods available; all are reported to give suspect results.

Contenu

Groundwater recharge concepts.- Groundwater recharge concepts.- An unexpected factor affecting recharge from ephemeral river flow in SWA/Namibia.- On the continuity of aquifer systems on the crystalline basement of Burkina Faso.- Groundwater recharge estimation (Part 1): physical/chemical methods.- A review of some of the physical, chemical and isotopic techniques available for estimating groundwater recharge.- Evaporation in arid and semi-arid regions.- Satellite remote sensing and energy balance modeling for water balance assessment in (semi-)arid regions.- A proposed study of recharge processes in fracture aquifers of semi-arid Botswana.- Estimation of natural groundwater recharge under Saudi Arabian arid climatic conditions.- Solute profile techniques for recharge estimation in semi-arid and arid terrain.- Recharge estimation from the depth-distribution of environmental chloride in the unsaturated zone - Western Australian examples.- Natural recharge measurements in the hard rock regions of semi-arid India using tritium injection - a review.- Comparison of recharge estimates from injected tritium technique and regional hydrological modelling in the case of a granitic basin in semi-arid India.- Studies on natural recharge to the groundwater by isotope techniques in arid Western Rajasthan, India.- Groundwater recharge estimation (Part 2): numerical modelling techniques.- Numerical and conceptual models for recharge estimation in arid and semi-arid zones.- Methods for estimation of natural groundwater recharge directly from precipitation - comparative studies in sandy till.- The principles of inverse modelling for estimation of recharge from hydraulic head.- Estimating natural recharge of ground water by moisture accounting and convolution.- Natural ground water recharge estimation methodologies in India.- BALSEQ - a model for the estimation of water balances, including aquifer recharges, requiring scarce hydrologic data.- Applications and case studies.- Quantification of groundwater recharge in arid regions: a practical view for resource development and management.- Groundwater recharge studies in semi-arid Botswana - a review.- Rainfall-runoff-recharge relationships in the basement rocks of Zimbabwe.- Recharge characteristics of aquifers of Jeddah-Makkah Taif region.- Groundwater recharge and subsurface flow in the Comodoro Rivadavia area, Chubut Province, Argentina. Isotopic and hydrochemical study.- Groundwater recharge over Western Saudi Arabia.- Natural recharge of karst aquifers in Western Taurus region (southwestern Turkey).- Estimation of recharge of sand aquifer of the Island of Mannar Sri Lanka.- Groundwater recharge from three cheap and independent methods in the small watersheds of the rainforest belt of Nigeria.- Quantitative estimation of ground-water recharge in dolomite.- Quantitative estimation of ground-water recharge in the Pretoria-Rietondale area.- Analysis of long-duration piezometric records from Burkina Faso used to determine aquifer recharge.- Humid zone recharge: a comparative analysis.- Humid and arid zone groundwater recharge - a comparative analysis.- List of participants.