Modeling flow and transport in irrigation catchments: 2. Spatial application of subcatchment model

Abstract

Abstract. An alternative to spatial distribution is presented for physically based process modeling of catchment flow and solute transport. The approach is based on an integral relation for catchment streamflow which describes the accumulation through the stream network of the hillslope contributions. This relation is redefined from integration with respect to position along the stream to an integral that is with respect to the physical properties determining the hillslope flow and transport with probability distributions to represent the range of parameter values and areas associated with these. Since the integrand is now a relatively smooth function of the variables of integration, standard numerical integration can be used to evaluate the catchment totals. The assumptions allowing this redefinition are that hillslope hydrology is primarily determined by driving forces that are local to the hillslope and that catchment flow can be lumped in time so that streamflow routing is not required. The interpolation of the integrand involved in the numerical integration results in significant savings over physically based spatially distributed catchment flow and transport models. The methodology is tested through application to an irrigated catchment where model simulations of flow and transport were found to be in close agreement with those observed.

Understanding salt mobilization from an irrigated catchment in south‐eastern Australia

“…Innovations (residuals from objective function (7)) were extensively checked for unexplained structure They were plotted against fitted values, model input variables and time, and did not display obvious patterns (data not shown). The ME obtained from cross‐validation (ME = 0·55) was similar to the cross‐validated error of the optimum‐sized tree from the CART analysis (Figure 4) and is also comparable to other much more complicated models applied to fit salt loads for the study catchment (Connell et al , 2001). ME at annual time steps (after aggregation of both measured and computed monthly salt loads) was 0·81.…”

“…The volume of groundwater discharging into the deeply incised drains is relatively small (10 mm/year on average) compared with the total drain flow (70 mm/year on average); however, due to the extremely high groundwater salinity (40 dS/m, Sinclair Knight Merz Pty Ltd, 2007), the amount of salt mobilized through groundwater discharge is substantial (150 000 t/year on average). Estimates by Connell et al (2001) suggest that the salt export to import ratio (salt import mainly through irrigation water) for study catchment could be as high as 10. Although different processes contribute to salt load at the catchment outlet (e.g.…”

“…Previous process studies in the study catchment were at the scale of an irrigation bay (Gilfedder et al , 2000a, 2000b) and at a sub‐catchment scale (Connell et al , 2001). The study by Gutteridge, Haskins & Davey Pty Ltd (1985) developed a model of flow and salinity for the whole study catchment.…”

Management of salt mobilisation in the irrigated landscape – A review of selected irrigation regions

“…Substantial amounts of salt can be mobilised in areas where surface drains intercept shallow saline water tables (Connell et al, 2003b). Designing surface drainage systems that do not intercept the water table will reduce salt mobilisation through groundwater seepage ).…”

Shallow landslide susceptibility assessment in a data-poor region of Guatemala (Comitancillo municipality)

“…The stability index mapping (SINMAP) model, developed by Pack et al (1998), integrates an infinite slope stability model and a steadystate hydrologic model, based on TOPMODEL (Beven and Kirkby, 1979;Connell et al, 2001). A detailed discussion of the SINMAP model is presented in Pack et al (1998).…”