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.
Employing evapotranspiration models is a widely used method to estimate reference evapotranspiration (ETREF) based on weather data. Evaluating such models considering site-specific boundary conditions is recommended to interpret ETREF-calculations in a realistic and substantiated manner. Therefore, we evaluated the ASCE standardized ETREF-equations at a subhumid site in northeastern Austria. We calculated ETREF-values for hourly and daily time steps, whereof the former were processed to sum-of-hourly values. The obtained data were compared to each other and to ETvalues measured by a weighing lysimeter under reference conditions. The resulting datasets covered daily data of the years 2004 to 2011. Sum-of-hourly values correlated well (r2 = 0.978) with daily values, but an RMSE of 0.27 mm specified the differences between the calculation procedures. Comparing the calculations to lysimeter measurements revealed overestimation of small ETREF-values and underestimation of large values. The sum-of-hourly values outperformed the daily values, as r2 of the former was slightly larger and RMSE was slightly smaller. Hence, sum-of-hourly computations delivered the best estimation of ETREF for a single day. Seasonal effects were obvious, with computations and measurements being closest to each other in the summer months.
Many soils and other porous media exhibit dual- or multi-porosity type features. In a previous study (Seki et al., 2022) we presented multimodal water retention and closed-form hydraulic conductivity equations for such media. The objective of this study is to show that the proposed equations are practically useful. Specifically, dual-BC (Brooks and Corey)-CH (common head) (DBC), dual-VG (van Genuchten)-CH (DVC), and KO (Kosugi)1BC2-CH (KBC) models were evaluated for a broad range of soil types. The three models showed good agreement with measured water retention and hydraulic conductivity data over a wide range of pressure heads. Results were obtained by first optimizing water retention parameters and then optimizing the saturated hydraulic conductivity (Ks) and two parameters (p, q) or (p, r) in the general hydraulic conductivity equation. Although conventionally the tortuosity factor p is optimized and (q, r) fixed, sensitivity analyses showed that optimization of two parameters (p + r, qr) is required for the multimodal models. For 20 soils from the UNSODA database, the average R2 for log (hydraulic conductivity) was highest (0.985) for the KBC model with r = 1 and optimization of (Ks, p, q). This result was almost equivalent (0.973) to the DVC model with q = 1 and optimization of (Ks, p, r); both were higher than R2 for the widely used Peters model (0.956) when optimizing (Ks, p, a, ω). The proposed equations are useful for practical applications while mathematically being simple and consistent.
About 75% of water for irrigation in Bangladesh comes from groundwater. As the crop yield is directly related to quality of water used for irrigation, an assessment of groundwater suitability for irrigation is essential for the growth of food production and poverty eradication. An attempt has been made in this paper to study the suitability of groundwater for irrigation in Bangladesh. Geographic information system (GIS) is used for the processing of groundwater quality data collected from 113 locations sporadically distributed over the country and the preparation of groundwater quality maps. The result shows that groundwater of the southwestern part of Bangladesh, which comprises 22.5% area of the country, is highly affected by salinity and sodium hazards. Groundwater in 10.54% area of the country is also contaminated by Arsenic above the permissible level recommended for irrigation. and Okolo 75 % vody pre závlahy v Bangladeši pochádza z podzemných vôd. Pretože úroda priamo závisí od kvality závlahovej vody, posúdenie vhodnosti vody pre závlahy je podstatné pre produkciu potravín a odstránenie chudoby. V štúdii je prezentovaný pokus o zhodnotenie vhodnosti podzemnej vody pre závlahy v Bangladeši. Na spracovanie údajov o kvalite podzemnej vody zo 113 lokalít rozmiestnených sporadicky po krajine a na prípravu máp kvality podzemnej vody sa použil geografický informačný systém (GIS). Výsledky naznačujú, že podzemná voda v juhozápadnej časti krajiny zaberajúcej 22,5 % jej plochy je silne ohrozená zasolenosťou a obsahom sodíka. Podzemná voda na ploche 10,54 % krajiny je tiež kontaminovaná obsahom arzénu nad prípustnú hranicu pre závlahovú vodu.