Gas production using hydraulic fracturing is well established in Marcellus shale deposits in USA. Shale gas production consumes significant amount of water and produces equal amounts of wastewater. It would be an exhausting endeavor for any water resource manager to understand the impact of shale gas production using hydraulic fracturing on water resources within the watershed with the plethora of available information. Rather, it would be much more convenient to have a single number or an index to summarize the impact. A Water Impact Index for Hydraulic Fracturing (WII4HF) is constructed in this study using indicators derived from available relevant parameters that are understandable, credible and integrative. The index is a modified form of Watershed Sustainability Index that is currently used to study impacts of other sectors on water resources. WIIHF incorporates technical, economic and legal/regulatory parameters in a holistic fashion. WII4HF is constructed as a function of four weighted indicators, hydrology (H), environment (E), life (L) and policy (P). Each indicator is constructed with equally important parameters that are expressed in three levels, Pressure-State-Response (PSR). PSR helps to link cause-action-effect relationship. The impact matrix is constructed as WII4HF = W(a, b, c, d)*I(H,E,L,P), where, W is the weight row vector with a + b + c + d = 1, and I is the indicator column vector. The indicator ranges are equally divided into five scale scores, (0, 0.25, 0.5, 0.75, 1). WII4HF and every indicator are in the range, (0-1). The following parameters are tentatively identified for estimating the I(H,E,L,P); a. available water quantity and water quality parameters of intake water and wastewater (for H), b. chemical spills and aesthetics of the water bodies (for E), c. costs of water and wastewater treatments and recreational water (for L), and d. legal and institutional policies (for P). However, the specific parameters selected to compute WII4HF depend on the data availability in a county. Each indicator score is calculated as the average of each parameter score that is an average of PSR scores of that parameter. PSR score scales for each parameter are defined based on the literature values and expert opinions. In this study, an equal weight vector W(0.25, 0.25, 0.25, 0.25) is assigned. WII4HF is being tested for selected counties in Pennsylvania and Ohio. Once tested, it can serve as a decision making tool for assessing the impacts.

WII4HF: A conceptual model for computing water impact index for hydraulic fracturing

249th National Meeting (2015)

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