Prospectus

Michigan Technological University

INTRODUCTION

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Nearly half of the population of Nicaragua resides in rural communities where access to water is limited to ground water wells, or in many cases of people living in extreme poverty use surficial water sources. Due to the low population density in rural areas, a single well may serve small groups of families. Therefore ground water extraction in a watershed is characterized by numerous wells with a maximum depth of 200 ft.. Reliance on groundwater in rural Nicaragua has increased considerably since the introduction of rope-pump wells in the 1980s. Since 1985 almost all perforated and dug wells have been equipped with rope pumps due to its simple design, low cost, reliability, and ease in repairing. The success of these wells has helped improve the livelihoods of rural farming families, thus leading to the installation of thousands of rope pump wells in Nicaragua since this period.

Although the use of groundwater is important in rural zones of Nicaragua, little information about aquifers and well behavior exists. The situation is complicated for many reasons, including: lack of economic resources to perform hydrogeologic investigations, complex fractured bedrock aquifers, difficulties in accessing wells, and lack of a characterization method appropriate for use in the types of wells used in many areas. Like many countries in the developing world, ground water resources are utilized with little understanding of aquifer characteristics, leading to unmanaged use. This type of activity frequently causes unsatisfactory well performance: significant drops in water table levels, well interference, and changes in water quality. In Nicaragua it is common that the winter rains do no adequately recharge hard rock aquifers and well users frequently suffer the debilitating effects of dry wells towards the end of summer.

A method to approximate the quantity of available water during the dry season, and the abstraction rate appropriate to ensure its continued use during that period, would aid rural farmers whose wells consistently become dry in the summer. I propose a method adapted from Herbert et al. (1992), which requires a series of pump tests in the well performed over the course of a week just after the seasonal rains have ceased. The results from these tests will be used to project the behavior of the well as the phreatic level changes over the course of the dry season. From these estimates, yield predictions can be made to ensure continual use of the well throughout the summer. This method appears to be simple and easily adaptable to rope pump wells. The results can greatly improve individual well owners’ abilities to regulate well use without expensive aquifer characterization.