Modelling the Potential of Integrated Vegetation Bands (IVB) to Retain Stormwater Runoff on Steep Hillslopes of Southeast Queensland, Australia

Abstract

Rainfall intensity is predicted to increase under a changing climate, leading to increased risks of hillslope erosion, downstream sedimentation and flooding. For many catchments used for grazing and agricultural land uses, it will become increasingly important to maintain ecohydrological functioning despite climatic extremes. One means to achieve this is through strategic reforestation using locally endemic species, in spatial configurations that effectively intercept, retain or and redistribute overland flows. This paper adopts a modelling approach for investigating the potential of one such design termed "integrated vegetation bands" (IVB), to increase the retention of runoff across steep hillslopes, particularly in the sub-tropics where rainstorms are becoming increasingly intense. A spatially distributed simulation model (MIKE-SHE) was applied to a steep, grazed catchment (Maronghi Creek catchment, Southeast Queensland, Australia) to compare stormwater runoff characteristics between: (1) the existing pasture land cover; and (2) a series of hypothetical IVB added across this pasture land. The IVB were approximately 20 m wide, and configured at 5% gradient towards ridgelines. Results for estimates of overland flow depth and infiltration (spatial), and accumulative water balance (temporal), confirm that OPEN ACCESSLand 2015, 4 712 the area of hillslope retaining > 10 mm/day more runoff increased by 22% under IVB compared to the pasture land use. Excluding the IVB themselves, the area of hillslope where runoff retention increased was 11%. During the most intense rainfall, IVB held up to 25% greater water depth and had 10% greater infiltration at the hillslope scale. At the sub-catchment scale, discharge decreased by 7% and infiltration increased by 23%. The findings for sub-tropical landscapes presented here are consistent with studies conducted in temperate regions. Based on the results of this preliminary modelling work, the IVB concept has been established as a paired-catchment field trial in a high rainfall catchment in Southeast Queensland, Australia.

The Integration of Ecosystem Services in Planning: An Evaluation of the Nutrient Retention Model Using InVEST Software

“…While the spatial distribution of the majority of ES was directly understandable (e.g., habitat quality, carbon sequestration, crop production, crop pollination, and water yield), the nutrient retention and sediment retention models presented a distribution dependent from the DEM, because the final output depends on gravitational models, vegetation, and soil characteristics [34,36,38,40,48,49].…”

Surface water as a cause of land degradation from dryland salinity

“…These are based on catchment area as defined by an upslope area of a pit-filled (coarse-resolution; 10 m) DEM. This is likely to significantly overestimate actual contributing catchment area, particularly in agricultural landscapes with banks and farm hillslopes dams harvesting surface water and low-gradient valley floors where the catchment area will be dynamic with depression storage and activation (Ryan et al, 2015;Callow and Smettem, 2009;Callow et al, 2007). Significant surface flows not recorded in this gauging network are captured and stored on hillslopes in farm dams (Ryan et al, 2015;Callow and Smettem, 2009).…”

“…For low-gradient and lower-rainfall zones (< 600 mm yr −1 ), there has been little-to-no evidence of revegetation impacts on groundwater at the scale it has been implemented at Johnsen et al, 2008), but it remains a popular approach in attempts to combat salinity and provide biodiversity and ecosystem service benefits (Cramer and Hobbs, 2002;Halse et al, 2003;Pannell, 2008). Ryan et al (2015) provide an interesting paradigm to consider in the contact of this work on how hillslope vegetation and surface water management can be integrated. In the valley floor, the broad-based channel is a high-cost intervention but offers a potential to address some processes causing salinity and in some parts of the landscape.…”

Modelling Agroforestry’s Contributions to People—A Review of Available Models

“…Plant growth and the presence of trees changes the surface roughness. A modelling study for wide tree strips in Australia showed a strong effect on the soil moisture distribution by changes in surface roughness and infiltration capacity [103], which is missing in available integrated crop-tree interaction models.…”