The impact of grazing cattle on soil physical properties and nutrient concentrations in overland flow from pasture, Part B

This report has been prepared as part of the Environmental Research Technological Development and Innovation Programme 2000–2006. The programme is financed by the Irish Government under the National Development Plan 2000–2006.End of project reportThe loss of nutrients from agricultural land to water bodies is a serious concern in many countries. To gain information on the contribution of grazing animals to diffuse nutrient losses from pasture areas to water, this study looked at the impact of cattle on nutrient concentrations in overland flow and on soil hydrology (bulk density, macroporosity and resistance to penetration). Rainfall simulations to produce overland flow were conducted and soil physical measurements were taken on experimental plots assigned to one of two treatments: 1) cattle had unrestricted access to the plot; 2) cattle could graze the plot but they could neither walk on the plot area nor deposit excrements on it. Areas to which the cattle had free access were characterised by 57%-83% lower macroporosity, by 8%-17% higher bulk density and by 27%-50% higher resistance to penetration than areas from which the cattle were excluded. The nutrients in overland flow from grassland that were affected by the presence of grazing animals were mainly the particulate nitrogen, the organic phosphorus and the potassium concentrations. Overall, the presence of cattle had a longer lasting effect on the soil hydrological parameters measured than on the nutrient concentrations in overland flow.Environmental Protection Agenc

Studi Kasus Kualitas Air Overland Flow di Permukiman Banteng, Sinduharjo, Sleman, YOGYAKARTA

Pertambahan penduduk berpengaruh pada bertambahnya aktivitas manusia yang dapat menurunkan kualitas lingkungan, khususnya kualitas air. Overland flow yang terjadi setiap hujan membawa berbagai pencemar, yang berasal dari kegiatan manusia. Tujuan penelitian ini adalah mengetahui karakteristik kualitas air overland flow dari parameter TSS, DHL, Nitrat, Nitrit, Fosfat, dan pH, dan mengetahui sumber pencemar serta kaitannya dengan aktivitas manusia. Metode penelitian ini adalah menggunakan uji laboratorium untuk data kualitas air dan wawancara terstruktur untuk data aktivitas manusia. Hasilnya menunjukkan bahwa air overland flow tercemar, melebihi baku mutu air kelas 2 menurut Peraturan Gubernur DIY Nomor 20 Tahun 2008, kecuali pH. Aktivitas manusia yang berpengaruh pada pencemaran overland flow adalah limbah dari kegiatan berkebun, pekarangan, hewan peliharaan, dan limbah domestik

A Model for TSUnami FLow INversion from Deposits (TSUFLIND)

Modern tsunami deposits are employed to estimate the overland flow characteristics of tsunamis. With the help of the overland-flow characteristics, the characteristics of the causative tsunami wave can be estimated. The understanding of tsunami deposits has tremendously improved over the last decades. There are three prominent inversion models: Moore advection model, Soulsby's model and TsuSedMod model. TSUFLIND incorporates all three models and adds new modules to better simulate tsunami deposit formation and calculate flow condition. TSUFLIND takes grain-size distribution, thickness, water depth and topography information as inputs. TSUFLIND computes sediment concentration, grain-size distribution of sediment source and initial flow condition to match the sediment thickness and grain size distribution from field observation. Furthermore, TSUFLIND estimates the flow speed, Froude number and representative wave amplitude. The model is tested by using field data collected at Ranganathapuram, India after the 2004 India Ocean tsunami. TSUFLIND reproduces the field measurement grain-size distribution with less than 5% error. Tsunami speed in this test case is about 4.7 m/s at 150 meters inland and decreases to 3.3 m/s 350 meters inland from the shoreline. The estimated wave amplitude of the largest wave for this test case is about 5 to 7 meters

Spatiotemporal variability of hydrologic soil properties and the implications for overland flow and land management in a peri-urban Mediterranean catchment

Planning of semi-urban developments is often hindered by a lack of knowledge on how changes in landuse affect catchment hydrological response. The temporal and spatial patterns of overland flow source areas and their connectivity in the landscape, particularly in a seasonal climate, remain comparatively poorly understood. This study investigates seasonal variations in factors influencing runoff response to rainfall in a peri-urban catchment in Portugal characterized by a mosaic of landscape units and a humid Mediterranean climate. Variations in surface soil moisture, hydrophobicity and infiltration capacity were measured in six different landscape units (defined by land-use on either sandstone or limestone) in nine monitoring campaigns at key times over a one-year period. Spatiotemporal patterns in overland flow mechanisms were found. Infiltration-excess overland flow was generated in rainfalls during the dry summer season in woodland on both sandstone and limestone and on agricultural soils on limestone due probably in large part to soil hydrophobicity. In wet periods, saturation overland flow occurred on urban and agricultural soils located in valley bottoms and on shallow soils upslope. Topography, water table rise and soil depth determined the location and extent of saturated areas. Overland flow generated in upslope source areas potentially can infiltrate in other landscape units downslope where infiltration capacity exceeds rainfall intensity. Hydrophilic urban and agricultural-sandstone soils were characterized by increased infiltration capacity during dry periods, while forest soils provided potential sinks for overland flow when hydrophilic in the winter wet season. Identifying the spatial and temporal variability of overland flow sources and sinks is an important step in understanding and modeling flow connectivity and catchment hydrologic response. Such information is important for land managers in order to improve urban planning to minimize flood risk

A physical model considered the effect of overland water flow on rainfall-induced shallow landslides

Abstract Background It is well know that many shallow landslides are triggered by rainfalls. In previous studies of shallow landslide models, the effect of overland water flow on slope stability was ignored. Results In this paper, a physical model considered the effect of overland water flow on rainfall-induced shallow landslides is derived and applied to predict the landslides. The slope stability model is developed by considering the depth of overland water flow in infinite slope stability theory. Hillslope hydrology is modelled by coupling the overland uniform water flow equation with Rosso’s seepage flow equation. And then, the model is used to assess the slope stability in Dujiangyan of China, and the results is compare with Rosso’s model. Conclusions This model is simple, but has the capability of taking into account the effect of overland water flow in the triggering mechanism of shallow landslide. The results of case study show that the overland water flow can make an obvious effect on shallow landslides, so it is quite important to consider the overland water flow in shallow landslide hazard assessment. </jats:sec

The Identification of Sites and Farming Systems Prone to Pollution by Surface Runoff.

End of Project ReportThere is mounting evidence that overland flow from land contributes to pollution of surface water. No convenient method exists to identify fields that generate overland flow. Therefore the WT model has been developed to predict overland flow from any small parcel of land. Water table tubes and flow meters were installed in three sites in Wexford and Carlow. The water table data, along with rainfall and evaporation data, were entered into the WT model to calculate overland flow and other parameters over a 7-month period. Additional measurements of water table level were taken using maximum level indicators with a view to reducing field costs. All three sites had layers of sand in the sub-soil. It is likely that the sand allowed water to flow under the soil and contributed to overland flow. Values from the WT model matched the field measurements of water table closely and predicted overland flow with reasonable accuracy. One pipe in each field was identified which could indicate when the field was sufficiently dry for spreading slurry. The maximum level indicators recorded water table accurately. However, the lack of synchronisation of this data, with weather data, reduced slightly the precision of the model. The WT model can identify fields prone to overland flow and show when a field is sufficiently dry to accept slurry. Proposed economies promise to reduce the cost of investigation

Hydrological heterogeneity in Mediterranean reclaimed slopes: runoff and sediment yield at the patch and slope scales along a gradient of overland flow

Hydrological heterogeneity is recognized as a fundamental ecosystem attribute in drylands controlling the flux of water and energy through landscapes. Therefore, mosaics of runoff and sediment source patches and sinks are frequently identified in these dry environments. There is a remarkable scarcity of studies about hydrological spatial heterogeneity in restored slopes, where ecological succession and overland flow are interacting. We conducted field research to study the hydrological role of patches and slopes along an "overland flow gradient" (gradient of overland flow routing through the slopes caused by different amounts of run-on coming from upslope) in three reclaimed mining slopes of Mediterranean-continental climate. We found that runoff generation and routing in non-rilled slopes showed a pattern of source and sink areas of runoff. Such hydrological microenvironments were associated with seven vegetation patches (characterized by plant community types and cover). Two types of sink patches were identified: shrub &lt;i&gt;Genista scorpius&lt;/i&gt; patches could be considered as "deep sinks", while patches where the graminoids &lt;i&gt;Brachypodium retusum&lt;/i&gt; and &lt;i&gt;Lolium perenne&lt;/i&gt; dominate were classified as "surface sinks" or "runoff splays". A variety of source patches were also identified spanning from "extreme sources" (&lt;i&gt;Medicago sativa&lt;/i&gt; patches; equivalent to bare soil) to "poor sources" (areas scattered by dwarf-shrubs of &lt;i&gt;Thymus vulgaris&lt;/i&gt; or herbaceous tussocks of &lt;i&gt;Dactylis glomerata&lt;/i&gt;). Finally, we identified the volume of overland flow routing along the slope as a major controlling factor of "hydrological diversity" (heterogeneity of hydrological behaviours quantified as Shannon diversity index): when overland flow increases at the slope scale hydrological diversity diminishes

Dynamic inundation simulation of storm water interaction between sewer system and overland flows

Copyright © 2002 Taylor & FrancisThis is the Author's Accepted Manuscript of an article published in the Journal of the Chinese Institute of Engineers (2002), available online at: http://www.tandfonline.com/10.1080/02533839.2002.9670691An improved urban inundation model, coupling a 2D non‐inertia overland flow model with a storm water management model, is adopted to simulate inundation in urban areas. The model computes, not only the overland runoff and the water overflow through manholes where surface runoff exceeds the capacity of storm sewers, but also the bidirectional flow interactions between sewers and overland runoff. The model was verified by a typhoon event in Nov. 2000, which resulted in serious inundation in the Mucha area of Taipei City. The result shows that the present model indeed improves simulation accuracy over the earlier model, and can be used to provide a more reliable flood mitigation design

Estimating water flow through a hillslope using the massively parallel processor

A new two-dimensional model of water flow in a hillslope has been implemented on the Massively Parallel Processor at the Goddard Space Flight Center. Flow in the soil both in the saturated and unsaturated zones, evaporation and overland flow are all modelled, and the rainfall rates are allowed to vary spatially. Previous models of this type had always been very limited computationally. This model takes less than a minute to model all the components of the hillslope water flow for a day. The model can now be used in sensitivity studies to specify which measurements should be taken and how accurate they should be to describe such flows for environmental studies