Managed Aquifer Recharge Using Multiwell Aquifer Storage Recovery Systems and Enhanced Infiltration Systems

Abstract

More than 1200 managed aquifer recharge (MAR) projects are being operated across the world to manage water resources by increasing rainfall recharge. Therefore, effective implementation of MAR systems is very important. This dissertation aims to provide a framework for designing and operating MAR systems such that water can be effectively stored in aquifers to raise groundwater elevations. This dissertation also provides guidelines for using stormwater to operate MAR in Harris County, Texas.

The first study identifies that the hydrogeological and operational parameters have a significant impact on the recovery of potable water and the energy efficiency of the multiwell Aquifer Storage Recovery systems. An important outcome of this study is that in order to maximize recovery and energy efficiency in multiwell systems, it is better to build fewer, but larger wells. However, the gains from doing so may be offset by the cost incurred for their construction. Aquifer properties also dictate the capacity of the wells and hence can serve as a limitation for multiwell systems. The methods and results from this study can be used to develop guidelines for effective and energy-efficient operation of multiwell ASR systems.

In the second study, a feasibility analysis was conducted to assess if MAR techniques could be used to control floods. But the geology of Harris County, limited infiltration capacity and available storage space in the area were found to be adequate for groundwater recharge and stormwater management but insufficient to control floods. Lissie and Willis formations in the northwestern and western part of Harris County are favorable for enhanced infiltration owing to their high surficial hydraulic conductivity. Beaumont formation with low permeability clays in southeastern region of the County is suitable for dry wells since it would, otherwise, inhibit infiltration of water into the subsurface.

The third study is a pilot study carried out in a detention basin to evaluate if enhanced infiltration systems could be successfully implemented in Harris County to promote recharge. Trenches backfilled with gravel and recycled concrete aggregates yield highest mean cumulative drainage of 3.3 m over two years. Soil amendment registers a mean cumulative drainage 0.7 times that of trenches while control yields 0.6 times that of trenches over the same time period. Groundwater quality did not alter much except for its salinity content.