Prediction of the long-term groundwater recharge by hydropedotransfer functions

A method is outlined to predict actual evapotranspiration and groundwater recharge considering climate, soil and depth to groundwater

Seasonality of meteorological drought parameters in Germany and their trends due to climate change

Climate change as a global problem affects the world on different scales, but its impact differs strongly between regions. Beside temperature, precipitation is another key element of the climatic system with at least the same importance. Regarding the precipitation regime, not only changes in the mean values have been detected, but also in the occurrence of extreme events and shifts in the seasonal distribution of precipitation throughout the year. With this background, our study investigates trends of meteorological drought in Germany as an example of what happens in a temperate climate zone. As indicators of dry spells we used the highest annual number of consecutive dry days, and the lowest precipitation within 40 days during one year as a new index. In addition, we analysed the annual and monthly total number of precipitation-free days as well as the total precipitation and its daily average on a monthly basis as further meteorological parameters. The results show an overall increase of the annual precipitation along with a decrease of the number of dry days per year. The highest annual number of consecutive dry days has also been decreasing, which means that dry spells are interrupted more often by significant precipitation and therefore are shorter. In accordance with the annual precipitation, the lowest precipitation during 40 consecutive days has also increased. As expected, the calculated linear trends of the parameters vary within the country and show a seasonal shift with stronger changes in certain month regarding the monthly precipitation, with a clear increase during the winter months. The results obtained using only precipitation-based meteorological parameters and our new index are in accordance with other results from the literature

Awareness and use of intertrochanteric osteotomies in current clinical practice. An international survey

Current literature shows that intertrochanteric osteotomies can produce excellent results in selected hip disorders in specific groups of patients. However, it appears that this surgical option is considered an historical one that has no role to play in modern practice. In order to examine current awareness of and views on intertrochanteric osteotomies among international hip surgeons, an online survey was carried out. The survey consisted of a set of questions regarding current clinical practice and awareness of osteotomies. The second part of the survey consisted of five clinical cases and sought to elicit views on preoperative radiological investigations and preferred (surgical) treatments. The results of our survey showed that most of these experts believe that intertrochanteric osteotomies should still be performed in selected cases. Only 56% perform intertrochanteric osteotomies themselves and of those, only 11% perform more than five per year. The responses to the cases show that about 30–40% recommend intertrochanteric osteotomies in young symptomatic patients. This survey shows that the role of intertrochanteric osteotomies is declining in clinical practice

Simulating future salinity dynamics in a coastal marshland under different climate scenarios

Salinization is a well‐known problem in agricultural areas worldwide. In the last 20–30 yr, rising salinity in the upper, unconfined aquifer has been observed in the Freepsumer Meer, a grassland near the German North Sea coast. For investigating long‐term development of salinity and water balance during 1961–2099, the one‐dimensional Soil–Water–Atmosphere–Plant (SWAP) model was set up and calibrated for a soil column in the area. The model setup involves a deep aquifer as the source of salt through upward seepage. In the vertical salt transport equation, dispersion and advection are included. Six different regional outputs of statistical downscaling methods were used as climate scenarios. These comprise different rates of increasing surface temperature and different trends in seasonal rainfall. The simulation results exhibit opposing salinity trends for topsoil and deeper layers. Although projections of some scenarios entail decreasing salinities near the surface, most of them project a rise in subsoil salinity, with the strongest trends of up to +0.9 mg cm−3 100 yr−1 at −65 cm. The results suggest that topsoil salinity trends in the study area are affected by the magnitude of winter rainfall trends, whereas high subsoil salinities correspond to low winter rainfall and high summer temperature. How these projected trends affect the vegetation and thereby future land use will depend on the future management of groundwater levels in the area

Prediction of long-term groundwater recharge by using hydropedotransfer functions

The investigations to estimate groundwater recharge were performed. Improved consideration of soil hydrologic processes yielded a convenient method to predict actual evapotranspiration and hence, groundwater recharge from easily available data. For that purpose a comprehensive data base was needed, which was created by the simulation modelSWAPcomprising 135 different site conditions and 30 simulation years each. Based upon simulated values of actual evapotranspiration, a transfer function was developed employing the parameter b in the Bagrov differential equation dEa/dP = 1- (Ea/Ep)b. Under humid conditions, the Bagrov method predicted long-term averages of actual evapotranspiration and groundwater recharge with a standard error of 15 mm year-1 (R = 0.96). Under dry climatic conditions and groundwater influence, simulated actual evapotranspiration may exceed precipitation. Since the Bagrov equation is not valid under conditions like these, a statistic-based transfer function was developed predicting groundwater recharge including groundwater depletion with a standard error of 26mm(R = 0.975). The software necessary to perform calculations is provided online

D:\D\Int-Agrophysics\27-1\Miegel\Miegel.vp

A b s t r a c t. The investigations to estimate groundwater recharge were performed. Improved consideration of soil hydrologic processes yielded a convenient method to predict actual evapotranspiration and hence, groundwater recharge from easily available data. For that purpose a comprehensive data base was needed, which was created by the simulation model SWAP comprising 135 different site conditions and 30 simulation years each. Based upon simulated values of actual evapotranspiration, a transfer function was developed employing the parameter b in the Bagrov differential equation dE a /dP = 1-(E a /E p ) b . Under humid conditions, the Bagrov method predicted long-term averages of actual evapotranspiration and groundwater recharge with a standard error of 15 mm year -1 (R = 0.96). Under dry climatic conditions and groundwater influence, simulated actual evapotranspiration may exceed precipitation. Since the Bagrov equation is not valid under conditions like these, a statistic-based transfer function was developed predicting groundwater recharge including groundwater depletion with a standard error of 26 mm (R = 0.975). The software necessary to perform calculations is provided online. K e y w o r d s

Application of HEC-HMS Model for Flow Simulation in the Lake Tana Basin: The Case of Gilgel Abay Catchment, Upper Blue Nile Basin, Ethiopia

Understanding the complex relationships between rainfall and runoff processes is necessary for the proper estimation of the quantity of runoff generated in a watershed. The surface runoff was simulated using the Hydrologic Modelling System (HEC-HMS) for the Gilgel Abay Catchment (1609 km2), Upper Blue Nile Basin, Ethiopia. The catchment was delineated and its properties were extracted from a 30 m × 30 m Digital Elevation Model (DEM) of the Lake Tana Basin. The meteorological model was developed within HEC-HMS from rainfall data and the control specifications defined the period and time step of the simulation run. To account for the loss, runoff estimation, and flow routing, Soil Conservation Service Curve Number (SCS-CN), Soil Conservation Service Unit Hydrograph (SCS-UH) and Muskingum methods were used respectively. The rainfall-runoff simulation was conducted using six extreme daily time series events. Initial results showed that there is a clear difference between the observed and simulated peak flows and the total volume. Thereafter, a model calibration with an optimization method and sensitivity analysis was carried out. The result of the sensitivity analysis showed that the curve number is the sensitive parameter. In addition, the model validation results showed a reasonable difference in peak flow (Relative Error in peak, REP = 1.49%) and total volume (Relative Error in volume, REV = 2.38%). The comparison of the observed and simulated hydrographs and the model performance (NSE = 0.884) and their correlation (R2 = 0.925) showed that the model is appropriate for hydrological simulations in the Gilgel Abay Catchment