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Roman cisterns served as rainwater storage devices for centuries and are densely distributed in parts of northern Jordan. A major earthquake hit the region ca. A.D. 750 and in a short time many settlements were abandoned. As a consequence, most cisterns were not maintained, and they filled with sediments that today provide a postabandonment depositional record. In two field surveys, we mapped the locations of more than 100 cisterns in the Wadi Al-Arab basin and selected two for detailed stratigraphic analysis that included 14C and optically stimulated luminescence dating. Catchment basin area for each cistern was determined by differential GPS. Both cisterns filled with sediments after the great earthquake and consequent abandonment of the region. Calculated sediment volumes are translated to long-term average sediment export rates of 2.6–6.6 t ha−1a−1, which are comparable to erosion and sediment yield rates from other studies within the Mediterranean region. Our pilot study suggests that this approach can be applied elsewhere to calculate long-term sediment export rates on hill slopes containing relict cisterns.

Over the last few decades many quantitative erosion studies have revealed that olive orchard expansion and increased mechanization in southern European countries have led to increased soil erosion under olive trees. Consequently, these studies have suggested different methods of mitigation. In light of the 2014 European trading zone expansion to countries east and south of the Mediterranean, a further intensification of olive plantations is postulated to meet market demands. To attain first medium-term estimates of erosion in Northern Jordan and its driving factors, a new method measuring olive mounds was implemented. Seven fields with clearly erosive structures were chosen throughout the Wadi Al-Arab catchment in Northern Jordan. Topographic measurements were used to reconstruct the historical and recent surface level and calculate the volume eroded since the planting of the trees. A total of 81 bulk density measurements and 14 tree cores allowed the estimation of the soil loss in tons per hectare. The combination of modified land use map and slope information helped to identify similar olive fields with high erosive potential. Results show that the method provides medium-term quantitative estimates for averaged soil loss consistent with some existing results from similar research areas in the Mediterranean. They clearly indicate the significant potential for erosion in olive orchards with around 95 ± 8 t ha − 1 yr − 1 . Tillage practice and water erosion were identified as critical erosion processes, both depending on tillage characteristics, tillage timing, and soil parent material. The investigated fields represent about 19% of the catchment's surface area and are likely to contribute to the measured yearly sediment yield that fills up the Wadi Al-Arab reservoir with sediments.

Recent studies about soil erosion show that erosion rates in winter can reach or exceed erosion induced by summer events. A factor of particular importance is the incidence of frozen soil, which modifies the surface runoff generation and also the erodibility of the soil. In this paper, investigations are conducted to characterize the snowmelt erosion events in the 1·44 km 2 ‘Schafertal’ research catchment that is located c. 150 km southwest of Berlin. Two runoff events of different initial conditions are compared and analysed. Although the net erosion rate in the catchment is relatively low, the described event with soil frost is considerably different from the event without soil frost. For example, the net erosion, maximum and median suspended sediment concentrations are significantly higher for the event with frozen soil. The results presented suggest that the sediment source areas differ for both situations. On one hand the channel or sediment flushing is identified as the source, while on the other hand hill slope processes and intra-storm variations are recognized for the soil frost situation. A model modification is presented to improve the estimation of spatial differentiation of surface runoff within the continuous hydrological model WaSim, which is linked to the erosion model AGNPS. Based on measurements of topsoil temperature at locations with diverse exposition and land use, an algorithm is developed. The average agreement of air temperature to the calculated topsoil temperature is r 2 = 0·75. The spatial information about soil frost is utilized to modify the infiltration characteristics of the soil. Hence, the spatial aspects of runoff generation in winter conditions and the related transport of sediment is considered in a more realistic way. The spatial results of the modelling are plausible but the estimation of erosion needs further improvement. Copyright © 2005 John Wiley & Sons, Ltd.

Temporal variability and spatial heterogeneity of surface runoff generation triggers the dynamics of source areas of sediment and sediment-associated nutrient transport. Reliable modelling of hydrological special situations i.e. snowmelt is of high importance for the quality of erosion and sediment yield modelling. Data from the research catchment Schafertal demonstrate the individuality of snowmelt events in terms of runoff coefficient and delivery ratio. This 1.44 km2 low mountain catchment is characterised by a high portion of arable land with a winter grain/winter rape crop rotation. The integrated winter erosion and nutrient load model (IWAN) considers these dynamic aspects by coupling a hydrological model with a sediment load model. Cell size of this raster-based approach is 10 × 10 m2. Additionally, snowmelt rill erosion is simulated with a newly developed physically based model that is firstly applied on a catchment scale. A sensitivity analysis of this model system component demonstrates the plausibility of the model approach and the overall robustness of the model system IWAN. The results of the long-term hydrological modelling from 1991 to 2003 are reliable and form the basis for the simulation of six snowmelt events which were observed in the Schafertal catchment. The estimated total runoff volumes for these events match the observations well. The modelled overland runoff coefficients vary from 0.001 to 0.72. The mean values of cell erosion, which were modelled with one set of parameters for all six events range from 0.0006 to 0.96 t ha− 1. The total modelled erosion for the events with unfrozen soil and low amount of surface runoff is of a factor 50 below those with partly frozen soil. In addition to these distinctions, the major differences are caused by flow accumulation in shallow depressions in variable parts of the catchment. However, the validation of these results on the single event scale is restricted due to limited spatial data. Total simulated sediment yield at the catchment outlet was as high as 13.84 t which underestimates the observed values, with the exception of one event. Oversimplification of the modelled channel processes may be a reason. The temporal variability and spatial heterogeneity of the surface roughness parameter, which was identified to be sensitive, also causes uncertainty in the parameter estimation. Despite these findings, the model system IWAN was applied successfully on the catchment scale and the simulated results are reliable.

Abstract Current research suggests that strategies to control sediment and phosphorus loss from non-point sources should focus on different runoff components and their spatial and temporal variations within the river basin. This is a prerequisite for determining effective management measures for reducing diffuse source pollution. Therefore, non-point source models, especially in humid climatic regions, should consider variable hydrologically active source areas. These models should be able to consider runoff generation by saturated overland flow, as well as Hortonian overland flow. A combination of the hydrological model WaSiM-ETH and the erosion and P-transport model AGNPS was chosen for this study. The models were run in the WaSiM runoff generation mode (Green & Ampt/TOPMODEL or Richards equation approach) and the SCS curve number mode to assess the effect of these different runoff calculation procedures on the dissolved phosphorus yield. A small and a medium-sized river basin, of the area of 1...

Rainfall erosivity is a basic mean of characterizing and understanding erosion processes. The empirically based EI 30 index, which is frequently used as part of the Universal Soil Loss Equation (USLE), has a number of limitations and requires adaptation for different climatic regions. In contrast, the A index, that was developed to calculate rainfall erosivity from rainfall simulation, is a physically based weight-function formula. This study demonstrates the functionality of this index using calculations for a number of rainfall events from two Russian regions as well as from Sardinia/Italy. Descriptive statistics and correlation analysis show, that values of the A index can replace with high accuracy the calculation of the EI 30 with a relation of 1:1 without data adaptation for the three test regions, which vary in climate and rainfall development. Although the values of erosivity for both indices are of high similarity, differences occur for single rainfall events with high internal variability. The results indicate a good estimation of rainfall erosivity for single rainfall events with the physically based A index. As there is a lack of data and an adaptation has to be carried out for the EI 30 index to fit the climatic conditions, it is feasible to substitute the EI 30 values with a calculation of the A index.