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Davis, CA, United States

Davids J.C.,Davids Engineering Inc. | Davids J.C.,California State University, Chico | Mehl S.W.,California State University, Chico
Groundwater | Year: 2015

Most surface water bodies (i.e., streams, lakes, etc.) are connected to the groundwater system to some degree so that changes to surface water bodies (either diversions or importations) can change flows in aquifer systems, and pumping from an aquifer can reduce discharge to, or induce additional recharge from streams, springs, and lakes. The timescales of these interactions are often very long (decades), making sustainable management of these systems difficult if relying only on observations of system responses. Instead, management scenarios are often analyzed based on numerical modeling. In this paper we propose a framework and metrics that can be used to relate the Theis concepts of capture to sustainable measures of stream-aquifer systems. We introduce four concepts: Sustainable Capture Fractions, Sustainable Capture Thresholds, Capture Efficiency, and Sustainable Groundwater Storage that can be used as the basis for developing metrics for sustainable management of stream-aquifer systems. We demonstrate their utility on a hypothetical stream-aquifer system where pumping captures both streamflow and discharge to phreatophytes at different amounts based on pumping location. In particular, Capture Efficiency (CE) can be easily understood by both scientists and non-scientist alike, and readily identifies vulnerabilities to sustainable stream-aquifer management when its value exceeds 100%. © 2015, National GroundWater Association. Source

Davids Engineering Inc. | Date: 1992-12-17

falafel patties, grape leaves, tahini, greek salad dressing, foule (boiled, mashed fava beans with garlic and salt), and mosaka. taboulli, spinach pie, broccoli cheese pie, baklava, and namura (sweet honey cake with nut topping).

Davids Engineering Inc. | Date: 1995-05-09

homous (hummus) and babaganouge.

Davids Engineering Inc. | Date: 1993-03-04

magazine publication devoted to entertaining and informing the members of the baby boom generation.

Steele D.D.,North Dakota State University | Thoreson B.P.,Davids Engineering Inc. | Hopkins D.G.,North Dakota State University | Clark B.A.,Davids Engineering Inc. | Tuscherer S.R.,North Dakota State University
Irrigation Science | Year: 2014

Excessive precipitation since 1993 has produced extensive flooding in the Devils Lake basin in northeastern North Dakota, USA. Irrigation of agricultural crops has been proposed as a flood mitigation tool. Ten test fields were equipped with center pivot irrigation systems to compare test field evapotranspiration (ET) with ET for crops in the predominantly nonirrigated basin. An irrigation scheduling analysis indicated 2006 was a favorable year to estimate the maximum ET gains achievable via irrigation. An ET map for 2006 using the Surface Energy Balance Algorithm for Land (SEBAL) for 54 % of the basin, and land use and soil survey data, was used to compare ET estimates at the test fields with ET estimates across the study area. May–September ET was estimated by SEBAL as 394 mm for wheat and 435 mm for corn across the study area, while corn ET at irrigated test sites was 452 mm. Because the 17-mm ET advantage by irrigating corn was substantially smaller than the 41-mm ET advantage for corn versus wheat, we conclude widespread irrigation development to mitigate flooding is not justified. Coarse-textured soils exhibited some seasonal ET deficits, but their small areal extents and parcel sizes offer virtually no opportunity for flood mitigation. © 2014 Springer-Verlag Berlin Heidelberg. Source

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