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Hydrograph Analysis (hydrograph + analysis)

Distribution by Scientific Domains
Engineering100%

Selected Abstracts

Estimating Ground Water Recharge from Topography, Hydrogeology, and Land Cover

GROUND WATER, Issue 1 2005
Douglas S. Cherkauer
Proper management of ground water resources requires knowledge of the rates and spatial distribution of recharge to aquifers. This information is needed at scales ranging from that of individual communities to regional. This paper presents a methodology to calculate recharge from readily available ground surface information without long-term monitoring. The method is viewed as providing a reasonable, but conservative, first approximation of recharge, which can then be fine-tuned with other methods as time permits. Stream baseflow was measured as a surrogate for recharge in small watersheds in southeastern Wisconsin. It is equated to recharge (R) and then normalized to observed annual precipitation (P). Regression analysis was constrained by requiring that the independent and dependent variables be dimensionally consistent. It shows that R/P is controlled by three dimensionless ratios: (1) infiltrating to overland water flux, (2) vertical to lateral distance water must travel, and (3) percentage of land cover in the natural state. The individual watershed properties that comprise these ratios are now commonly available in GIS data bases. The empirical relationship for predicting R/P developed for the study watersheds is shown to be statistically viable and is then tested outside the study area and against other methods of calculating recharge. The method produces values that agree with baseflow separation from streamflow hydrographs (to within 15% to 20%), ground water budget analysis (4%), well hydrograph analysis (12%), and a distributed-parameter watershed model calibrated to total streamflow (18%). It has also reproduced the temporal variation over 5 yr observed at a well site with an average error < 12%. [source]

Estimation of irrigation flow by hydrograph analysis in a complex agricultural catchment in subtropical China

HYDROLOGICAL PROCESSES, Issue 10 2007
Jia-Liang Tang
Abstract Estimating the amount of irrigation water is challenging at the catchment scale because of the difficulties in direct measurement and interactions between the flow components. The objectives of the study were to characterize the catchment flows in an agricultural catchment with an irrigation system in subtropical China and to estimate catchment irrigation flow using hydrograph analysis methods. A weighting model and multiple regression models were established to estimate catchment irrigation outflow according to the hydrographs of the inflows and outflows of the catchment. The multiple regression models took into consideration the drainage time of base flow, resulting in better estimation on an event and annual basis. Using the MR-6d method, the estimated irrigation outflows amounted to 3700 mm, 2600 mm and 2760 mm during 2001, 2002 and 2003 respectively, which covered 70%, 60% and 64% respectively of the total catchment outflows in the corresponding years. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Comparison of stormflow responses of surface-mined and forested watersheds in the Appalachian Mountains, USA

HYDROLOGICAL PROCESSES, Issue 16 2006
Timothy L. Negley
Abstract The results of a hydrological analysis that was conducted as part of a larger, multifaceted, collaborative effort to quantify ecosystem functions in watersheds subjected to land-use and land-cover change are presented. The primary goal of the study was to determine whether a small watershed in the Appalachian region (USA) that was recently subjected to surface mining and reclamation practices produces stormflow responses to rain events that are different from those produced by a nearby reference watershed covered by young, second-growth forest. Water balances indicated that runoff yields did not vary significantly between the two watersheds on an annual basis. Statistically significant differences (p,0·05) in runoff responses were observed on an event basis, however, with the mined/reclaimed watershed producing, on average (a) higher storm runoff coefficients (2·5×), (b) greater total storm runoff (3×), and (c) higher peak hourly runoff rates (2×) when compared with the reference watershed. Results of a unit hydrograph analysis also showed, unexpectedly, that the modelled unit responses of the two watersheds to effective rainfall pulses were similar, despite the noted differences in land cover. Differences in stormflow responses were thus largely explained by dramatic reductions in cumulative rates of rainfall abstraction (measured using infiltrometers) attributable to soil compaction during land reclamation. Additional field hydrological measurements on other mined watersheds will be needed to generalize our results, as well as to understand and predict the cumulative hydrological impacts of widespread surface mining in larger watersheds and river basins. Copyright © 2006 John Wiley & Sons, Ltd. [source]

EFFECTS OF TOPOGRAPHY AND SOIL PROPERTIES ON RECHARGE AT TWO SITES IN AN AGRICULTURAL FIELD,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2000
Geoffrey N. Delin
ABSTRACT: Field experiments were conducted from 1992 to 1995 to estimate ground water recharge rates at two sites located within a 2.7-hectare agricultural field. The field lies in a sand plain setting in central Minnesota and is cropped continuously in field corn. The sites are located at a topographically high (upland) site and a topographically low (lowland) site in an effort to quantify the effects of depression focusing of recharge. Three site-specific methods were used to estimate recharge rates: well hydrograph analysis, chlorofluorocarbon age dating, and an unsaturated zone water balance. All three recharge methods indicated that recharge rates at the lowland site (annual average of all methods of 29 cm) exceeded those at the upland site (annual average of 18 cm). On an annual basis, estimates by the individual methods ranged from 12 to 44 percent of precipitation at the upland site and from 21 to 83 percent at the lowland site. The difference in recharge rates between the sites is primarily attributed to depression focusing of surface water runon at the lowland site. However, two other factors were also important: the presence of thin lamellae at the upland site, and coarser textured soils below a depth of 1.5 m at the lowland site. [source]