Semi-arid Catchment Research Articles

Integrating Aquatic and Terrestrial Carbon Fluxes to Assess the Net Landscape Carbon Balance of a Highly Erodible Semiarid Catchment

AbstractThe magnitude of the carbon (C) sink due to terrestrial primary production may be overestimated if the C losses through fluvial networks are not properly accounted for. In this study, we hypothesize that terrestrial‐aquatic C transfers represent a major loss of the terrestrial C sink in semiarid catchments. To test the hypothesis, we assessed the net landscape carbon balance (NLCB) of a highly erodible catchment on the semiarid Chinese Loess Plateau by compiling terrestrial net ecosystem productivity (NEP) estimates and aquatic fluxes of downstream C export, emission of CO2 and CH4, and C burial. Our results showed that, despite the severe erosion and strong C mobilization, this catchment was a net C sink (NLCB = 48.3–54.8 Mg C km−2 year−1). Downstream C export at catchment outlet and evasion of CO2 and CH4 only offset terrestrial NEP by 7.7%–8.5% due largely to low flow discharge and small water surface area of the stream network. Furthermore, C burial in reservoirs played a considerable role, reducing an additional 7.5%–8.3% of the NEP. Altogether, approximately 84% of the net terrestrial C production was stored within the catchment. Our study reveals that semiarid catchments with widespread erosion and low terrestrial production remain a net C sink, although the magnitude is lower than those found in other climate zones. Our study further advocates the need to integrate terrestrial‐aquatic C transfer into a comprehensive net C balance accounting at the landscape scale. Ignoring the aquatic C loss will cause biased estimates of the overall C sink strength.

Integrating Geographical Information Systems and Remote Sensing for Identifying the Driving Factors of Dynamic Changes in Soil Erosion Over Semi-Arid Catchments in Southwest China

Integrating Geographical Information Systems and Remote Sensing for Identifying the Driving Factors of Dynamic Changes in Soil Erosion Over Semi-Arid Catchments in Southwest China

Topographically moderated soil water seasons impact vegetation dynamics in semiarid mountain catchments: Illustrations from the Dry Creek Experimental Watershed, Idaho, USA

AbstractWater stored in soils, in part, controls vegetation productivity and the duration of growing seasons in wildland ecosystems. Soil water is the dynamic product of precipitation, evapotranspiration and soil properties, all of which vary across complex terrain making it challenging to decipher the specific controls that soil water has on growing season dynamics. We assess how soil water use by plants varies across elevations and aspects in the Dry Creek Experimental Watershed in southwest Idaho, USA, a mountainous, semiarid catchment that spans low elevation rain to high elevation snow regimes. We compare trends in soil water and soil temperature with corresponding trends in insolation, precipitation and vegetation productivity, and we observe trends in the timing, rate and duration of soil water extraction by plants across ranges in elevation and aspect. The initiation of growth‐supporting conditions, indicated by soil warming, occurs 58 days earlier at lower, compared with higher, elevations. However, growth‐supporting conditions also end earlier at lower elevations due to the onset of soil water depletion 29 days earlier than at higher elevations. A corresponding shift in peak NDVI timing occurs 61 days earlier at lower elevations. Differences in timing also occur with aspect, with most threshold timings varying by 14–30 days for paired north‐ and south‐facing sites at similar elevations. While net primary productivity nearly doubles at higher elevations, the duration of the warm‐wet period of active water use does not vary systematically with elevation. Instead, the greater ecosystem productivity is related to increased soil water storage capacity, which supports faster soil water use and growth rates near the summer solstice and peak insolation. Larger soil water storage does not appear to extend the duration of the growing season, but rather supports higher growing season intensity when wet‐warm soil conditions align with high insolation. These observations highlight the influence of soil water storage capacity in dictating ecological function in these semiarid steppe climatic regimes.

Long-term water quality assessments under changing land use in a large semi-arid catchment in South Africa

Increasing nutrient loads from land use and land cover (LULC) change degrade water quality through eutrophication of aquatic ecosystems globally. The Vaal River Catchment in South Africa is an agriculturally and economically important area where eutrophication has been a problem for decades. Effective mitigation strategies of eutrophication in this region require an understanding of the relationship between LULC change and water quality. This study assessed the long-term impacts of LULC changes on nitrate (NO3-N) and orthophosphate (PO4-P) pollution in the lower Vaal River Catchment between 1980 and 2018. Multi-year LULC was mapped from Landsat imagery and changes were determined. Long-term trends in NO3-N and PO4-P loads and concentrations in river water samples were analysed, while multi-year LULC data were ingested into the Soil and Water Assessment Tool (SWAT) to simulate the impacts of LULC changes in NO3-N and PO4-P loads. Main LULC changes included an increase in the irrigated area by 262% and in built-up area by 33%. This occurred at the expense of cultivated dryland fields and rangelands. In situ data analysis showed that at the catchment inlet, PO4-P concentration and loads significantly increased, while NO3-N concentration and loads decreased between 1980 and 2018. At the catchment outlet, only PO4-P loads increased, while NO3-N loads and concentrations remained the same. SWAT simulations at the Hydrologic Response Unit scale showed that irrigated land was the largest contributor to NO3-N leaching per ha. Aggregation of nutrient loads by LULC type showed increased nutrient loads from irrigated and built-up areas over time, while loads from dryland areas decreased. At catchment scale, dryland remained an important contributor of the annual nutrient loads total because of its large area. In future, research efforts should focus on crop management practices to reduce nutrient loads.

Integrating Sediment (dis)Connectivity into a Sediment Yield Model for Semi-Arid Catchments

Soil erosion-associated sedimentation has become a significant global threat to sustainable land and water resources management. Semi-arid regions that characterise much of southern Africa are particularly at risk due to extreme hydrological regimes and sparse vegetative cover. This study aims to address the need for an erosion and sediment delivery model that successfully incorporates our conceptual understanding of sedimentation processes in semi-arid regions, particularly sediment storage and connectivity within a catchment. Priorities of the Semi-arid Sediment Yield Model (SASYM) were simplicity and practical applicability for land and water resource management while adhering to basic geomorphic and hydrological principles. SASYM was able to represent multiple sediment storages within a catchment to effectively represent a change in landscape connectivity over geomorphic timeframes. SASYM used the Pitman rainfall–runoff model disaggregated to a daily timescale, the Modified Universal Soil Loss Equation (MUSLE), incorporating probability function theory and a representation of sediment storages and connectors across a semi-distributed catchment. SASYM was applied to a catchment in the Karoo, South Africa. Although there were limited observed data, there was a historical dataset available for the catchment through dam sedimentation history. SASYM was able to effectively present this history and provide evidence for landscape connectivity change.

Changes in and Modelling of Hydrological Process for a Semi-Arid Catchment in the Context of Human Disturbance

Hydrological modelling is of critical importance to flood control. However, flood forecasting in semi-arid region is a great challenge to hydrologists, particularly in a changing environment. Taking the Zhulong River catchment located in north China as a case, the performance of GR4J model for hydrological modelling was investigated based on the analysis for changes in hydrological process of three periods defined as natural period (1967–1979), moderate human impact period (1980–1996) and intensive human impact period (1997–2015). Results show that 1) the annual precipitation and temperature of the catchment both presented upward trends, while the annual observed runoff exhibited a significant downward trend in the time span from 1967 to 2015; 2) the correlations between runoff and precipitation were comparatively higher on both monthly and annual scales in natural period than those in human disturbed periods; 3) both annual runoff and daily peak discharge in human disturbed periods decreased relative to those in natural period due to the environmental changes; 4) the GR4J model performed well for runoff simulations in natural period but gradually lost its applicability with the intensification of human activities. It is essential to improve the accuracy of hydrological modelling under a changing environment in further studies.

Effect of a reservoir network on drought propagation in a semi-arid catchment in Brazil

ABSTRACT Building reservoirs is a response to cope with drought in drylands. However, this human modification to the landscape may trigger both positive and negative effects. Here, we investigate how a network of reservoirs influences the propagation of meteorological drought (MD) into hydrological drought (HD) in a large semi-arid catchment in Brazil. We applied 12-month standardized indices to classify droughts. Then, the drought series were compared to each other. The downstreamness concept was used to describe the spatial water distribution. The onset of reservoir drought (RD) was much later than MD, but the delay between MD and RD peaks was even longer. Streamflow drought started with a small delay after MD, but it transformed into a similar RD. RD was initially more severe downstream. When the drought severity was at its highest, upstream and downstream RD equalized. The perceptual model of drought propagation may help in developing reservoir management systems in drylands.

Hydrologic similarity: Dimensionless runoff indices across scales in a semi-arid catchment

In this study, an assessment of similarity relationships across runoff measurements at various spatial scales was carried in a typical Sahelian landscape, under semi-arid climate in northern Burkina Faso (west African Sahel). The scales of observations considered are the plot scale (1 m2, 50 m2, 150 m2) and the sub-catchment scale (6.1 ha, 33.8 ha), with various soil surface conditions and slopes. These scales were monitored during six years (2010–2015) under natural rainfall. Based on monitoring data, a runoff potential index I1 and an effective runoff index I2 are developed, encapsulating the physical characteristics of the observation scale into dimensionless forms, hence reducing their sensitivity to the scale effects. These indices help in assessing hydrological similarity across measurement scales. Results showed that runoff decreases with the increase of the observation scale size. Besides, dimensionless indices vary following a logarithmic decay relationship with the scale size (R2 > 0.98). Such results highlight the non-linear nature of runoff processes and also promotes similarity analysis as a means to model hydrological processes through soil surface conditions and landscape descriptors.

Assessment of Streamflow from EURO-CORDEX Regional Climate Simulations in Semi-Arid Catchments Using the SWAT Model

This research studies the effect of climate change on the hydrological behavior of two semi-arid basins. For this purpose, the Soil and Water Assessment Tool (SWAT) model was used with the simulation of two future climate change scenarios, one Representative Concentration Pathway moderate (RCP 4.5) and the other extreme (RCP 8.5). Three future periods were considered: close (2019–2040), medium (2041–2070), and distant (2071–2100). In addition, several climatic projections of the EURO-CORDEX model were selected, to which different bias correction methods were applied before incorporation into the SWAT model. The statistical indices for the monthly flow simulations showed a very good fit in the calibration and validation phases in the Upper Mula stream (NS = 0.79–0.87; PBIAS = −4.00–0.70%; RSR = 0.44–0.46) and the ephemeral Algeciras stream (NS = 0.78–0.82; PBIAS = −8.10–−8.20%; RSR = 0.4–0.42). Subsequently, the impact of climate change in both basins was evaluated by comparing future flows with those of the historical period. In the RCP 4.5 and RCP 8.5 scenarios, by the end of the 2071–2100 period, the flows of the Upper Mula stream and the ephemeral Algeciras stream will have decreased by between 46.3% and 52.4% and between 46.6% and 55.8%, respectively.

Potential influence of climate and land-use changes on green water security in a semi-arid catchment

Abstract Temporal and spatial changes of green water (GW) security due to climate and land-use/land-cover (LULC) changes can be used to make the best decisions for sustainable GW management. In this study, simultaneous effects of climate and LULC changes on water resources in Kashafrood Basin were evaluated using the Soil and Water Assessment Tool (SWAT). A land change modeler was set up to monitor LULC, assess changes and make predictions. The MIROC-ESM model derived from Coupled Model Intercomparison Project Phase 5 under two representative concentration pathway (RCP) emission scenarios RCP2.6 and RCP8.5 was applied to evaluate the effects of climate change. Two indices of GW-Scarcity and GW-Vulnerability, representing GW-Security, were quantified using the GW-Footprint concept in Kashafrood Basin. The results show that the annual average of blue water was predicted to increase by 142–350%, and GW storage and the annual averages of GW flow were predicted to decrease by 12–65 and 8–20%, respectively, depending on emission scenarios and time. The GW-Security estimates in the entire basin suggest a better condition in the future by indicating 24–45 and 16–52% decreases in GW-Scarcity and GW-Vulnerability, respectively, depending on emission scenarios and time.

High spatial resolution simulation of profile soil moisture by assimilating multi-source remote-sensed information into a distributed hydrological model

Profile soil moisture (PSM), which represents soil moisture content over the whole soil layer depth, is a key variable to control plant growth, biological interactions, and streamflow generation, and its information plays a crucial role in hydrological analysis and agricultural water management. Recent studies have assimilated multi-source satellite PSM information into hydrological modelling to more accurately estimate real PSM. However, the PSM estimated from these studies are normally at coarse spatial resolution (i.e., larger than 25 × 25 km2). In this study, the high-resolution (1 × 1 km2) PSM are generated by assimilating multiple remote-sensed PSM data of coarse resolution into the Digital Elevation Model (DEM) based distributed rainfall-runoff model (DDRM) in three catchments (two humid catchments and one semiarid catchment) in China with the grid scale of 1 × 1 km2. The remote-sensed PSM data are pre-processed from two remote-sensed surface soil moisture datasets, i.e. the multi-satellite-retrieved soil moisture dataset released by the Europe Space Agency Climate Change Initiative (ESA CCI), and the soil moisture product from the Soil Moisture Active Passive (SMAP) satellite. The influence of remote-sensed datasets selection schemes (i.e. only ESA CCI, only SMAP, and ESA CCI and SMAP combined) on assimilation results are investigated. In the assimilation process, two updating schemes are considered, one is to only update the DDRM’s state variable, i.e. PSM, and the other updating both the parameters and PSM variable of the DDRM. Thus, six assimilation scenarios are set in the study, whose performances are compared with the DDRM without assimilation for different time periods, including the whole period, the dormant period and the growing period. Results indicate that in any periods, for any of remote-sensed datasets used for assimilation, either the state update or the parameter-state update can improve the accuracy of high-resolution (1 × 1 km2) PSM simulations by the DDRM. Besides, assimilating the SMAP PSM dataset into the DDRM has the potential to improve streamflow simulations for the three catchments. This study has shown that, by assimilating multi-source remote-sensed PSM into a high spatial resolution distributed hydrological model, i.e. DDRM, estimation of PSM can be improved over both the original remote-sensed PSM and the DDRM-simulated PSM.

Present and Future High-Resolution Climate Forcings over Semiarid Catchments: Case of the Tensift (Morocco)

In semiarid areas, the climate is characterized by strong spatiotemporal variability while the meteorological ground network is often very sparse. In this context, the spatial distribution of meteorological variables is thus a real issue for watershed hydrology, agronomy and the study of surface–atmosphere retroaction in these regions. The aim of this study is twofold: (1) to evaluate and to adapt a reanalysis system “Système d’Analyse Fournissant des Renseignements Adaptés à la Nivologie” (SAFRAN) to map the meteorological variables on the Tensift catchment (Morocco) between 2004 and 2014; (2) to project temperature and precipitation for the 2041–2060 horizon at high-resolution based on the Euro-CORDEX database at 12 km resolution (using two Representative Concentration Pathway -RCPs- scenarios and four Regional Climate Models), on the SAFRAN reanalysis and on a network of meteorological stations. SAFRAN was assessed: (1) based on leave-one-out for a station located in the plain and another in the mountains; (2) by comparison to another re-analysis system named the Meteorological Distribution System for High-Resolution Terrestrial Modeling (MicroMet); (3) by comparison to in situ measurements of snowfall at one station and to the daily Snow Cover Area derived from the Moderate-Resolution Imaging Spectroradiometer (MODIS) product at the catchment scale. The evaluation of the SAFRAN reanalysis showed that an irregular grid up to 1 km resolution is better for reproducing meteorological variables than the regular version of SAFRAN at 8 km, especially in mountains. The projection of the SAFRAN forcing is conducted in three steps corresponding to the three subsections below: (1) disaggregation of the Euro-CORDEX climate scenarios using the Q–Q approach based on stations data; (2) computation of the spatialized delta-change between historical and future Euro-CORDEX runs after Q–Q correction; (3) futurization of SAFRAN using the spatialized delta change values. The mountainous area is expected to face a higher increase in air temperature than the plains, reaching +2.5 °C for RCP8.5 and +1.71 °C for RCP4.5 over 2041–2060. This warming will be accompanied by a marked decrease in precipitation (−16% for RCP8.5). These present and future spatialized data sets should be useful for impact studies, in particular those focusing on water resources.

A process‐based soil erosion model ensemble to assess model uncertainty in climate‐change impact assessments

AbstractThe impact of climate change on future soil loss is commonly assessed with soil erosion models, which are suggested to be an important source of uncertainty. Here, we present a novel soil erosion model ensemble to assess model uncertainty in climate‐change impact assessments. The model ensemble consists of five continuous process‐based soil erosion models that run at a daily time step (i.e., DHSVM, HSPF, INCA, MMF, SHETRAN). The models were implemented in the SPHY hydrological model and simulate detachment by raindrop impact, detachment by runoff, and immediate deposition. The soil erosion model ensemble was applied in a semiarid catchment in the southeast of Spain. We applied three future climate scenarios based on global mean temperature rise (+1.5, +2 and +3°C). Data from two contrasting regional climate models were used to assess how an increase and a decrease in projected extreme precipitation affect model uncertainty. Soil loss is projected to increase (up to 95%) and decrease (up to −30%) under climate change, mostly reflecting the change in extreme precipitation. Model uncertainty is found to increase with increasing slope, extreme precipitation and runoff, which reveals some inherent differences in model assumptions among the five models. Moreover, the model uncertainty increases in all climate change scenarios, independent of the projected change in annual precipitation and extreme precipitation. This stresses the importance to consider model uncertainty through model ensembles of climate, hydrology, and soil erosion in climate‐change impact assessments.

Controls on Streamflow Densities in Semiarid Rocky Mountain Catchments

Developing accurate stream maps requires both an improved understanding of the drivers of streamflow spatial patterns and field verification. This study examined streamflow locations in three semiarid catchments across an elevation gradient in the Colorado Front Range, USA. The locations of surface flow throughout each channel network were mapped in the field and used to compute active drainage densities. Field surveys of active flow were compared to National Hydrography Dataset High Resolution (NHD HR) flowlines, digital topographic data, and geologic maps. The length of active flow declined with stream discharge in each of the catchments, with the greatest decline in the driest catchment. Of the tributaries that did not dry completely, 60% had stable flow heads and the remaining tributaries had flow heads that moved downstream with drying. The flow heads were initiated at mean contributing areas of 0.1 km2 at the lowest elevation catchment and 0.5 km2 at the highest elevation catchment, leading to active drainage densities that declined with elevation and snow persistence. The field mapped drainage densities were less than half the drainage densities that were represented using NHD HR. Geologic structures influenced the flow locations, with multiple flow heads initiated along faults and some tributaries following either fault lines or lithologic contacts.

Impact of Land Use Change on Non-Point Source Pollution in a Semi-Arid Catchment under Rapid Urbanisation in Bolivia

Changes in pollution pressure exerted on the Rocha River in Bolivia from diffuse sources were assessed using potential non-point pollution indexes (PNPI) for 1997 and 2017. PNPI is a simple, low-effort, time- and resource-saving method suitable for data-scarce regions, as it works at catchment level with commonly available geographical data. Land use type (obtained by Landsat imagery classification), runoff (determined by runoff coefficient characterisation) and distance to river network (calculated at perpendicular distance) were each transformed into corresponding indicators to determine their relative importance in generating pollution. Weighted sum, a multi-criteria analysis tool in the GIS environment, was used to combine indicators with weighting values. Different weighting values were assigned to each of the indicators resulting in a set of six equations. The results showed that higher PNPI values corresponded to human settlements with high population density, higher runoff values and shorter distance to river network, while lower PNPI values corresponded to semi-natural land use type, lower runoff coefficient and longer distances to river. PNPI values were positively correlated with measured nitrate and phosphate concentrations at six sub-catchment outlets. The correlation was statistical significant for phosphate in 2017. Maps were produced to identify priority source areas that are more likely to generate pollution, which is important information for future management.

Optimization of Hydrologic Response Units (HRUs) Using Gridded Meteorological Data and Spatially Varying Parameters

Although complex hydrological models with detailed physics are becoming more common, lumped and semi-distributed models are still used for many applications and offer some advantages, such as reduced computational cost. Most of these semi-distributed models use the concept of the hydrological response unit or HRU. In the original conception, HRUs are defined as homogeneous structured elements with similar climate, land use, soil and/or pedotransfer properties, and hence a homogeneous hydrological response under equivalent meteorological forcing. This work presents a quantitative methodology, called hereafter the principal component analysis and hierarchical cluster analysis or PCA/HCPC method, to construct HRUs using gridded meteorological data and hydrological parameters. The PCA/HCPC method is tested using the water evaluation and planning system (WEAP) model for the Alicahue River Basin, a small and semi-arid catchment of the Andes, in Central Chile. The results show that with four HRUs, it is possible to reduce the relative within variance of the catchment up to about 10%, an indicator of the homogeneity of the HRUs. The evaluation of the simulations shows a good agreement with streamflow observations in the outlet of the catchment with an Nash–Sutcliffe efficiency (NSE) value of 0.79 and also shows the presence of small hydrological extreme areas that generally are neglected due to their relative size.

Effects of model calibration on hydrological and water resources management simulations under climate change in a semi-arid watershed

Semi-arid regions are known for erratic precipitation patterns with significant effects on the hydrological cycle and water resources availability. High temporal and spatial variation in precipitation causes large variability in runoff over short durations. Due to low soil water storage capacity, base flow is often missing and rivers fall dry for long periods. Because of its climatic characteristics, the semi-arid north-eastern region of Brazil is prone to droughts. To counter these, reservoirs were built to ensure water supply during dry months. This paper describes problems and solutions when calibrating and validating the eco-hydrological model SWIM for semi-arid regions on the example of the Pajeú watershed in north-eastern Brazil. The model was calibrated to river discharge data before the year 1983, with no or little effects of water management, applying a simple and an enhanced approach. Uncertainties result mainly from the meteorological data and observed river discharges. After model calibration water management was included in the simulations. Observed and simulated reservoir volumes and river discharges are compared. The calibrated and validated models were used to simulate the impacts of climate change on hydrological processes and water resources management using data of two representative concentration pathways (RCP) and five earth system models (ESM). The differences in changes in natural and managed mean discharges are negligible (< 5%) under RCP8.5 but notable (> 5%) under RCP2.6 for the ESM ensemble mean. In semi-arid catchments, the enhanced approach should be preferred, because in addition to discharge, a second variable, here evapotranspiration, is considered for model validation.

Assessment of subsurface riverbed clogging by fine sediments in a semi-arid catchment of north-western Algeria

In semi-arid regions, natural and anthropogenic disturbances increase the input of fine particles and their subsequent accumulation in streambeds sediment. The clogging of streambeds sediment is caused by the infiltration of fine particles at depth, reducing hydraulic conductivity (K) and hyporheic flow. Grain-size distribution and streambed vertical K were estimated using hyporheic sediment samples collected from ten stations in the Tafna River catchment during two hydrological periods of high and low water in order to investigate spatiotemporal variations and the variables influencing hydraulic conductivity. During the wet season, the upstream part of the catchment had significantly higher coarse sand content, with K measured to be three times greater than downstream. During low flow periods, there were significantly more fine particles (clay and silt) downstream, which were negatively correlated with K. Increases in clay and silt were the main cause of sediment clogging in the downstream part of catchment. However, within-group PCA showed that geomorphology had no significant influence on hyporheic sediment clogging. This study demonstrated that the process of streambed sediment clogging was influenced by the accumulation of fine particles and organic matter, which significantly contributed to the clogging of the downstream hyporheic zone, thus decreasing hydraulic conductivity despite prevailing geomorphology.

Responses of macroinvertebrate community metrics to urban pollution in semi-arid catchments around the city of Bulawayo, Zimbabwe

River health monitoring is becoming increasingly important because of the anthropogenic activities that continue to impact on water quality and biodiversity of aquatic systems. This study aimed at identifying and evaluating macroinvertebrate community-based metrics that best respond to degradation due to urban pollution in riverine systems of Bulawayo, Zimbabwe. Data (physicochemical variables and macroinvertebrate specimens) were collected from 17 sites over 3 seasons. The sites were selected across an impairment gradient comprising less impacted, moderately impacted and heavily impacted sites. Heavily impacted sites had the highest levels of total dissolved solids, conductivity, salinity, turbidity, total phosphates, total nitrogen, chemical oxygen demand and sedimentary zinc. Dissolved oxygen was significantly highest in less impacted sites. Sensitivity of 24 macroinvertebrate metrics to this impairment gradient were assessed. A total of 5 metrics were identified as sensitive to modifications in water quality due to urban pollution. These metrics were taxon richness, South African Scoring System (SASS5) score, average score per taxon (ASPT), percentage collectors and percentage scrapers. The selected metrics will be useful for the monitoring and assessment of the studied riverine systems and can be further integrated into one multimetric index that combines a range of indices and allows the integration of ecological information for better management of aquatic ecosystems in this region.

Impacts of precipitation and topographic conditions on the model simulation in the north of China

AbstractThe evaluation of hydrological models for a specific catchment is normally based on the model performance according to the selected performance criteria. However, the catchment rainfall-runoff characteristics could be used for the selection of a suitable hydrological model in study area, which, also, for the problem solve of the model application in ungauged basins. In this study, six conceptual models were applied in three semi-humid or semi-arid catchments to investigate the correlation between catchment characteristics and model structure selection. In addition, the impacts of precipitation and topography in model simulation were analyzed. The results show that runoff generation are highly impacted by catchment topographic index and land cover change, and the influence of slope for river channel is greater than mean slope for the whole catchment due to the runoff generation for partial area. For the catchments under similar climate condition, the impact of topographic features for runoff generation process is greater than the difference of precipitation. It indicates that for a specific catchment, the selection of appropriate model should base on better understanding of the rainfall-runoff relationship. The method of incorporating additional runoff generation module in the traditional model can significantly improve the accuracy of flood simulation.