Semi-distributed Water Balance Model Research Articles

Semi-distributed water balance modelling using Budyko hypothesis, land information and hydroclimatic data with various time scales

ABSTRACT In this paper, a comprehensive semi-distributed water balance model is presented for basins under anthropogenic impacts. It benefits from data in different time resolutions for estimation of surface and groundwater exchanges and water withdrawals for various purposes. Ground-based data such as vegetation cover and topography have been used to determine the model parameters. The performance of the proposed model was tested for 38 sub-basins in Iran representing various climate conditions, vegetation covers, and agricultural practices. The results demonstrated a good performance in terms of estimating streamflows at the basin outlet, with more than 90% of sub-basins having a correlation coefficient above 0.9. However, the model showed a relatively weaker performance in the estimation of annual aquifer storage volume change. Correlation coefficients above 0.6 were calculated for more than half of the aquifers in the study area.

Scale Effects of Water Saving on Irrigation Efficiency: Case Study of a Rice-Based Groundwater Irrigation System on the Sanjiang Plain, Northeast China

This research analyzed the scale effect of water saving in Bielahonghe (BLH) Basin, a rice-cultivating district on the Sanjiang Plain, Northeast China. Water budgets with different surface irrigation water supply ratios and water-saving measures were simulated with a semi-distributed water balance model. PFnws, representing the ratio of rice evapotranspiration to net water supply (the total amount of irrigation and precipitation minus the amount of water reused), was employed to assess the water use efficiency. Seven spatial scales (noted from S1 to S7), ranging from a single field (317.87 ha) to the whole basin (about 100,800 ha) were determined. PFnws values were quantified across scales and several water-saving measures, including water-saving irrigation regimes, canal lining, and a reduction of the surface water supply ratio (SWSR). The results indicated that PFnws increased with scale and could be calculated by a fitted power function (PFnws = 0.736Area0.033, R2 = 0.58). Furthermore, PFnws increased most prominently when the scale increased from S1 to S2. The water-saving irrigation regime (WSIR) had the most substantial water-saving effect (WSE) at S1. Specifically, PFnws improved by 21.2% at S1 when high-intensity WSIR was applied. Additionally, the WSE values of S3 and S5 were slightly higher than at other scales when the branch canal water delivery coefficient increased from 0.65 to 0.80 through canal lining. Furthermore, the PFnws at each scale varied with SWSR. Specifically, PFnws from S3 to S7 improved as SWSR decreased from 0.4 to 0.3 but remained approximately constant when SWSR decreased from 0.3 to 0.

Assessment of interbasin groundwater flows between catchments using a semi-distributed water balance model

In hydrological modeling it is often assumed that the aquifers boundaries are formed by the geographical demarcation of the catchment. However, this assumption is rarely met, given the existence of groundwater flows going beyond the catchment limits. The assessment of interbasin groundwater flows is crucial when managing water resources in areas where baseflows are mainly formed by groundwater, especially when catchments are managed separately. Aiming at estimating the volume and direction of the main groundwater flows, this work presents a new methodological approach for hydrological modeling. This approach employs a semi-distributed water balance model created with lumped models. This model is formulated in such a way that a part of the groundwater discharge of a specific catchment can become baseflows in other catchments, which helps characterize interbasin groundwater flows. This methodology is applied in the headwater of the Segura River Basin (southeast of Spain), where groundwater plays an important role in surface hydrology. The catchments are modeled with a high goodness of fit, and the main interbasin groundwater flows between them is evaluated, proving its importance in the characterization of hydrological modeling.

Evaluating the bio-hydrological impact of a cloud forest in Central America using a semi-distributed water balance model

Abstract Water scarcity poses a major threat to food security and human health in Central America and is increasingly recognized as a pressing regional issues caused primarily by deforestation and population pressure. Tools that can reliably simulate the major components of the water balance with the limited data available and needed to drive management decision and protect water supplies in this region. Four adjacent forested headwater catchments in La Tigra National Park, Honduras, ranging in size from 70 to 635 ha were instrumented and discharge measured over a one year period. A semi-distributed water balance model was developed to characterize the bio-hydrology of the four catchments, one of which is primarily cloud forest cover. The water balance model simulated daily stream discharges well, with Nash Sutcliffe model efficiency (E) values ranging from 0.67 to 0.90. Analysis of calibrated model parameters showed that despite all watersheds having similar geologic substrata, the bio-hydrological response the cloud forest indicated less plantavailable water in the root zone and greater groundwater recharge than the non cloud forest cover catchments. This resulted in watershed discharge on a per area basis four times greater from the cloud forest than the other watersheds despite only relatively minor differences in annual rainfall. These results highlight the importance of biological factors (cloud forests in this case) for sustained provision of clean, potable water, and the need to protect the cloud forest areas from destruction, particularly in the populated areas of Central America.

The impact of different elevation steps on simulation of snow covered area and the resulting runoff variance

Abstract. This study analyses the impact of vertical model discretisation on modelling snow covered area and the consequential effects on runoff formation of the semi-distributed water balance model HQsim. Therefore, the parameters relevant for snow modelling are varied within the frame of a uniformly distributed Monte Carlo Simulation (MCS). Since the model is based on the hydrological response unit (HRU) approach, the effect of building the HRUs with different elevation steps (250 m and 500 m) is tested for two alpine catchments. In total 5000 parameter combinations were generated for simulation. The results of modelled snow covered area were compared with thirty MODIS (Moderate Resolution Imaging Spectroradiometer) snow cover maps for the melting periods in 2003–2011. Based on a contingency table the comparisons were evaluated by different skill measures. Finally, the pareto optimal parameter settings of each skill measure were detected. Evaluation of runoff variability within the MCS and their pareto optimal runs show reduced variances of model output resulting from an improved simulation of the snow covered area.

Hydrologic Analysis of Rainfed Rice Areas Using a Simple Semi-distributed Water Balance Model

We analyzed the hydrologic characteristics of the Nong Saeng Basin (19.72 km2) in northeast Thailand. Because the land use in this basin is very complex, applying a fully distributed model would be extremely difficult. Therefore, we developed a semi-distributed hydrologic model for this basin. The hydrologic model comprised upland, paddy, and pond models. The new bucket model was applied for upland fields, and a modified tank model was used for the paddy and pond models. In addition, water movement between different land uses was considered. The results showed that the hydrologic model developed for the study basin performed extremely well if water movement between different land uses was considered. We simulated the water storage characteristics for two sub-catchments within the basin: sub-catchment 1 included few earthen weirs, whereas sub-catchment 2 included several earthen weirs. Owing to the earthen weirs, the maximum differences in ponding paddy water were 19,997 m3 in 2002 and 16,897 m3 in 2003, corresponding to 48% and 41% of the total volume of ponds in sub-catchment 1 (41,287 m3), respectively. If earthen weirs were to be constructed over the entire basin, the annual runoff from the basin would decrease by 2.0–3.2%. Although the decrease of the annual runoff is little, the maximum differences between the daily runoffs under real and simulated conditions in terms of percentage differences are −44.3% in September 2002 and −36.5% in September 2003, and it is found that the downstream impacts are quite large at the end of rainy season.

A monthly stream flow model for estimating the potential changes of river runoff on the projected global warming

Hydrological processes in high altitude mountainous regions differ from those in more temperate regions, primarily due to such influences as cold temperatures, large and rapid change in surface energy balance during snowmelt, a long period at low-temperature environmental condition and the existence of permafrost. A physically based, semi-distributed water balance model to quantitatively simulate the hydrological processes and stream flow, as well as to estimate the potential consequences of projected global warming on stream flow for such high altitude mountainous regions was constructed. Distributed meteorological data from the interpolation of the point measurements by means of a digital elevation model (DEM) of the basin, such as air temperature, precipitation, snowfall ratio, wind speed, etc., have been used as model input. Several other hydrological parameters, such as soil moisture content and evapotranspiration, which are essential in simulation of river runoff in a water balance state, were estimated by the combination of Landsat TM and a DEM with the utilization of the distributed meteorological data. The model uses only a few crucial parameters for calibration, and the model structure is based upon estimating the stream flow components. Simulated results of spatially distributed soil moisture content, evapotranspiration and monthly discharge yield reasonable agreement, both spatially and temporally, to the field observations or the estimated results by the other approaches. This physically based model has the potential to project stream flow under the possible climate scenarios. Copyright © 2000 John Wiley & Sons, Ltd.