Subcatchment Area Research Articles

Response of sediments and phosphorus to catchment characteristics and human activities under different rainfall patterns with Bayesian Networks

The rainfall patterns play an important role in determining the response of Suspended Sediment (SS) and Total Phosphorus (TP) to influence factors, which is complex and needs to be better understood. The Bayesian Network (BN), with each variable depending on only its immediate parent variables, can help to describe the complex processes involved. In this study, BNs were developed to assess the impacts of catchment characteristics and human activities on SS and TP loads under different rainfall patterns in the Huaihe River Basin (HRB). The results showed that SS made significant contributions to TP in rivers which increased with the rainfall intensity. Catchment characteristics (sub-catchment area, slope and soil erosion area) affected the SS and TP loads; however the influence of human activities (sewage outfalls and land use) was more significant. With the rainfall intensity rising, farmland switched from a “sink” to a “source” of nutrients. When the antecedent three-day-average rainfall intensity was high but the current one was low, the farmland became the most significant source of SS and TP. The urbanization had significant positive effects on SS (ranging from 10.9% to 15.1%) and TP (ranging from 8.3% to 10.5%), which was insensitive to rainfall patterns as a result of the high proportions of impervious surface coverage in the urban area. These results improve our understanding of influence factors on river water quality and will contribute to effective water environment management for rivers.

Probability distribution of groundcover for runoff prediction in rangeland in the Burnett–Mary Region, Queensland

Considering the degree of spatial and temporal variation of groundcover in grazing land, it is desirable to use a simple and robust model to represent the spatial variation in cover in order to quantify its effect on runoff and soil loss. The purpose of the study was to test whether a two-parameter beta (β) distribution could be used to characterise cover variation in space at the sub-catchment scale. Twenty sub-catchments (area range 35.8–231km2) in the Burnett–Mary region, Queensland, were randomly selected. Thirty raster layers of groundcover at 30-m resolution were prepared for these 20 sub-catchments with the average cover for the 30 layers ranging from 24% to 91%. Three methods were used to test the appropriateness of the β distribution for characterising the cover variation in space: (i) visual goodness-of-fit assessment and Kolmogorov–Smirnov (K-S) test; (ii) the fractional area with cover ≤53%; and (iii) estimated runoff amount for a given rainfall amount for the area with cover ≤53%. The K-S test on 30×100 samples of groundcover showed that the hypothesis of β distribution for groundcover could not be rejected at P=0.05 for 97.5% of the cases. A comparison of the observed and β distributions in terms of the fractional area with cover ≤53% showed that the discrepancy was ≤8% for the 30 layers considered. A comparison in terms of the estimated runoff showed that results using the observed cover distribution and the β distribution were highly correlated (R2 range 0.91–0.98; Nash–Sutcliffe efficiency measure range 0.88–0.99). The mean absolute error of estimated runoff ranged from 0.98 to 8.10mm and the error relative to the mean was 4–16%. The results indicated that the two-parameter β distribution can be adequately used to characterise the spatial variation of cover and to evaluate the effect of cover on runoff for these predominantly grazing catchments.

Biodiversity, trait composition and ecological functioning: impacts of coastal urbanisation on subtropical mudflats

The world’s coastlines have become heavily modified over the last century, with the adjacent natural habitats declining in biodiversity and health under increasing pressure from urbanisation. In this study we assessed the structure and biological traits of macrofaunal assemblages from 24 south-east Queensland mudflats in order to determine whether ecological functioning (e.g. primary production, nutrient cycling) and the delivery of ecosystem services was affected by urbanisation. This work represents the most comprehensive assessment of mudflat assemblages in the region to date. The mudflats contained 50 macrofaunal taxa and so were comparable to other local intertidal systems. Summer assemblages contained more species, more individuals and had differing taxonomic composition. When indexed as a proportion of subcatchment area, urbanisation did not correspond to a clear impact on macrofaunal composition; rather, the nature of the industry or activity was critical. Mudflats from subcatchments with industries producing organic wastes significantly differed from subcatchments with <1.3% cover of these industries. Functioning was conserved in mudflats experiencing current levels of enrichment, but this may decline with growing pressure from human populations. The results of this study illustrate that large-scale spatial data, such as from satellites, can be used to detect the cumulative effects of urbanisation when the pressures are highly resolved.

Impact of agricultural land use on soil organic carbon sequestration at sub-catchment scale

Soil organic carbon (SOC) pool determines the potential of soil to perform ecosystem services and maintain climatic stability. Land use plays a significant role in determining the carbon (C) sequestration in soil. This study aimed to determine the impact of long-term agricultural land uses on SOC and other physico-chemical properties and to determine interrelationships between SOC stock and topographic variables at sub-catchment scale in upcountry of Sri Lanka. Soil samples were collected from surface (0-30 cm) and subsurface (30-60 cm) at 109 locations from vegetable (n = 42), tea (n = 44) and forest (n = 23) land uses in a sub-catchment (360 ha) in Nuwara Eliya. Average SOC in different land uses were compared by analysis of variance followed by Tukey post-hoc mean comparison. The largest surface SOC stock was observed in forested area (71.8 Mg/ha) followed by vegetable lands (61.8 Mg/ha) and it was significantly lesser in tea lands (50.7 Mg/ha). The forest soils showed the largest subsurface SOC stock (67.1 t/ha) as well, followed by tea (64.8 Mg/ha) and vegetable (57.9 Mg/ha) land uses. No significant relationship was observed between SOC stock and topographic variables, namely elevation, slope, wetness index and stream power index. This study concludes that the land use is a key determinant of the spatial heterogeneity of SOC and forest have the greater ability of sequestering C compared to vegetable and tea land uses in the studied sub-catchment area.

Interpreting nested storm event suspended sediment‐discharge hysteresis relationships at large catchment scales

AbstractReducing soil erosion and sediment delivery into rivers is a major aim for land management in New Zealand. Therefore, it is important to identify areas of sediment generation and their relationship to in‐stream suspended sediment concentrations and water quality attributes. It is possible to infer and assess sediment sources and dynamics using storm event suspended sediment concentration‐discharge hysteresis shape and loop direction. Research in small catchments has achieved some success; however, research in larger (>103 km2) catchments has shown the inherent difficulty of interpreting hysteresis patterns at larger scales. In this paper, we use a nested, long‐term suspended sediment monitoring program across a large catchment (3,903 km2: Manawatū in New Zealand) to address these challenges. We evaluate the hysteresis patterns of five major tributaries (subcatchment areas 329–1,298 km2) of the Manawatū River together with the hysteresis patterns at the gauged catchment outlet. Hysteresis patterns of the Manawatū subcatchments can be characterized as predominantly clockwise, that is, high hysteresis index (HI) value. Larger storms (discharge >2 × 107 m3) increase the likelihood of clockwise hysteresis directions, whereas smaller storms (discharge <2 × 107 m3) are more likely to be anticlockwise. The link between suspended sediment concentration‐discharge hysteresis and subcatchment sediment sources becomes increasingly attenuated within the larger subcatchments. High antecedent discharge negatively correlates to HI values, suggesting conditions immediately before the storm have an influence on whether the catchment is “primed” or “exhausted” with available sediment. The different storm categories indicate that within this catchment, whereas hysteresis patterns vary due to the spatial origin of discharge and sediment to some extent, storm magnitude has a stronger impact on hysteresis dynamics than spatial origin.

Tropical Coastal Wetlands Ameliorate Nitrogen Export During Floods

Wetlands can increase resilience to extreme climatic events and have a key role in protection and water quality improvement in coastal ecosystems. Studies in tropical coastal wetlands at a catchment scale are scarce, and most work has been undertaken on small, temperate wetlands. In this study, we tested whether natural coastal wetlands in a tropical catchment (Tully-Murray, Queensland, Australia) could ameliorate nitrogen (N) exported to the Great Barrier Reef during a flood event. We measured denitrification rates in different types of coastal wetlands (mangroves, saltmarshes, waterbodies with macrophytes, and floodplain wetlands dominated by Melaleuca spp.) to assess their potential contribution to N losses during the 6-day duration of a flood in March 2018. Denitrification potential was variable across the landscape, and we identified “hotspots” in sub-catchments with high NO−3-N concentrations (0.4–0.6 mg L−1) and large areas of wetlands (>800 ha, >40% of the sub-catchment). These hotspots can denitrify up to 10 t of NO−3-N per day during a flood. We used our measured denitrification rates to provide input parameters for a model that includes the main biogeochemical processes affecting N transformations within wetlands (nitrification, denitrification, plant uptake, sedimentation, anammox, and mineralization), and accounts for transport via the duration, depth, and flow of water. Model simulations of a sub-catchment of the Tully-Murray indicate that flood inundation of large areas of natural wetlands (>40% of the sub-catchment area) could potentially remove 70% of the incoming NO−3-N load in the first 24 h of the flood. The management and restoration of coastal tropical wetlands could play a critical role in sustaining the health of coastal ecosystems through water quality improvement.

Water quality indices as a tool for evaluating water quality and effects of land use in a tropical catchment

ABSTRACT Human actions are degrading water quality, affecting the health of ecosystems and the availability of potable water for human consumption. Therefore, the monitoring of water systems is essential for recovery and management purposes. This study aimed to investigate the water quality in the environmental protection area (EPA) of Itupararanga Reservoir (Brazil) using water quality indices, pointing out land uses that contributing to the deterioration of water quality. The spatial analysis involved the creation of land use and soil maps of the sub-catchment areas of Itupararanga. Water quality index (WQI), trophic state index (TSI), aquatic life index (ALI), index of minimum variables for the maintenance of aquatic life (IMVMAL) and metals pollution potential index (MPPI) were calculated. The land uses which can affect the water quality on long term were identified. TSI (mesotrophic and hypereutrophic) and ALI showed results above the recommended values were. MPPI presented high values for the elements Al, Cr and Fe. Principal component analysis (PCA) showed spatial variability in the reservoir. In conclusion, the sampling sites with lower water quality were Sorocabuçu and Una, followed by Sorocamirim. These sites probably explain the deteriorated water quality found in sampling point Res1 of the reservoir for all indices analysed.

Flood hydrograph prediction in a semiarid mountain catchment: The role of catchment subdivision

AbstractThe effect of different degrees of catchment subdivision coupled with the nonlinear storage–discharge relationship on hydrograph prediction is evaluated in a meso‐scale catchment in the Zagros mountain region, southwest of Iran. The catchment is divided into different sets of subcatchments based on catchment geomorphology, and runoff hydrographs are simulated for each set using a network‐based runoff routing model, watershed‐bounded network model. It is shown that, in the absence of fully distributed data, if a semidistribution of storage–discharge is taken into consideration in the modeling process, lumped rainfall data could provide valuable information on the hydrological response of catchment in data‐scarce regions, which are usually found in remote areas, such as mountains. Although the results suggest that catchment subdivision leads to more accurate results, a subcatchment area threshold of about 3% of the catchment extent is found. Below this, no further improvement in simulation accuracy can be achieved, probably because of the limitations of the data interpolation method used by the model.

A carrying capacity framework for soil phosphorus and hydrological sensitivity from farm to catchment scales

Agricultural fields with above optimum soil phosphorus (P) are considered to pose risks to water quality and especially when those areas are coincident with hydrologically sensitive areas (HSAs) that focus surface runoff pathways. This is a challenge to manage in areas of agricultural intensity in surface water dominated catchments where water quality targets have to be met. In this study, a soil P survey of 13 sub-catchments and 7693 fields was undertaken in a 220km2 catchment. HSAs were also determined as the top 25th percentile risk from a runoff routing model that used a LiDAR digital elevation model and soil hydraulic conductivity properties. Distributions of these spatial data were compared with river soluble reactive phosphorus (SRP) concentration measured fortnightly over one year. The results showed that 41% of fields exceeded the agronomic optimum for soil P across the sub-catchments. When compared with the available water quality data, the results indicated that the high soil P carrying capacity area of the sub-catchments was 15%. Combining high soil P and HSA, the carrying capacity area of the sub-catchments was 1.5%. The opportunities to redistribute these risks were analysed on fields with below optimum soil P and where HSA risk was also minimal. These ranged from 0.4% to 13.8% of sub-catchment areas and this limited potential, unlikely to fully reduce the P pressure to over-supplied fields, would need to be considered alongside addressing this over-supply and also with targeted HSA interception measures.

English

Forests are important in the lives of local communities as they provide poles for construction, wood fuel for cooking, help reduce soil erosion and provide various foods and medicines due to biodiversity. Most local communities depend on forests in supplementing their livelihoods. At the moment, forests are being lost and it is important to understand the impacts of the lost. Therefore, the objective of the study was to provide a holistic evaluation of the impacts of deforestation on ecosystem services in Kamfinsa sub-catchment of Kitwe in Zambia. Loss of forest biomass, biodiversity, and soil erosion were key proxy variables for loss of ecosystem services. Geographical Information System (GIS) and Remote sensing techniques were used to assess the impacts on the ecosystem. The results showed that deforestation reached 576.3 ha per year during the period studied. The forest loss corresponds to an emission of 43.73 ton of carbon per hectare from above and below ground biomass valued at US$243.60 per hectare. According to this research soil erosion risk assessment, 1.59 ton of soil was lost per hectare per year, equivalent to US$ 57.20 loss per hectare. The indigenous forest cover reduced from 13,430.5 ha (1990) to 2,904.7 ha (2010), with a corresponding change in NDVI index for loss of forest vigor and biodiversity of 0.56 and 0.32, respectively. The major forest loss occurred from indigenous forests. The study has shown that deforestation in Kamfinsa sub-catchment area calls for the urgent promotion of an integrated and comprehensive approach to addressing the drivers of deforestation to ensure continued supply of ecosystem services. Key words: Carbon budget, carbon dioxide, emission, forestry, land degradation, natural resource management, remote sensing, water-shade.

The Application of Multi-Criteria Analysis Methods for the Determination of Priorities in the Implementation of Irrigation Plans

Irrigated agriculture has considerable impacts on the environment. To minimize negative effects and maximize positive effects, it is necessary to provide comprehensive analyses beyond the strictly technical domain. In this study, we apply a methodology for determining priorities in implementing irrigation plans using multi-criteria analysis methods on a specific case study area in the sub-catchment area of the Orljava River in Požega–Slavonia County, Croatia. Five potential irrigation areas (Orljava–Londža, Pleternica, Ovčare, Treštanovci, and Venje–Hrnjevac) were analyzed according to five selected criteria: environmental protection, water-related (four sub-criteria), social, economic, and time criteria with different criteria importance (weight). The aim of this study was to confirm the adequacy of using six multi-criteria analysis (MCA) methods (mostly used: PROMETHEE, AHP, ELECTRE TRI, and the less used: DEXi, PRIME, and PCA) in determining priorities for fulfilling irrigation plans, present models for preparation of the input data, apply certain methods, and compare the results on the selected case study area. The methods’ adequacy was confirmed during the research. Five of the six MCA methods identified the Ovčare area as the most appropriate for irrigation development (i.e., it has priority in implementing the irrigation plan). According to one (AHP) of the six methods, Orljava–Londža has more advantages over other areas. All MCA methods, except PCA, chose Venje–Hrnjevac as the least advisable (last to be implemented) alternative. Conclusions from this research confirm findings from recently published research regarding the application of MCA on water management problems.

Uncertainty in Catchment Delineations as a Result of Digital Elevation Model Choice

Nine digital elevation model (DEM) datasets were used for separate delineations of the Nam Co, Tibet catchment and its subcatchments, and these delineated areas were compared using the highest resolution dataset, TanDEM-X 12 m, as a baseline. The mean delineated catchment area was within 0.1% percent of the baseline delineation, with a standard error of the mean (SEM) that was 0.13% of the baseline. In a comparison of 49 subcatchment areas, TanDEM-X and ALOS datasets delineated similar areas, followed closely by SRTM 30 m, then SRTM 90 m, ACE2, and ASTER GDEM1. ASTER GDEM2 was a noteworthy outlier, having the largest mean subcatchment area that was nearly three times that of the baseline mean. Correlation coefficients were calculated for subcatchment parameters, SEM, and each DEM’s subcatchment area error. SEM had a weak but significant negative correlation with the mean and median slope. ASTER GDEM1 and GDEM2 were the only datasets that showed any significant correlations with the subcatchment environment variables, though these correlations were also weak. The 30 m posting ASTER GDEMs performed worse against the baseline than the other 30 m and 90 m datasets, showing that posting alone does not determine how good a dataset is. Our results show general small errors for catchment delineations, though there is the possibility for large errors, particularly in the older ASTER and SRTM datasets.

Runoff quantity response of three urban mountain parks-hilltop subtype in humid subtropical climate based on SWMM

With the development of sustainable stormwater management, urban parks have the advantages and necessities in constructing low impact development system to reduce and reuse stormwater. This study aims to understand the hydrological processes in small scale mountain watersheds based on three typical hilltop parks in Chongqing, China. Sub-catchment areas were divided into paved square type (PST), vegetation cover type (VCT) and mixed cover type (MCT). Native stromwater models by SWMM were created under 25 mm, 50 mm, 4 years and 20 years precipitation events to simulate the runoff quantity. The runoff quantity per unit area in different sub-catchments was provided as : PST > MCT >VCT. Runoff quantity affected by impervious surface percentage was the most significant compared to other parameters. Positive correlation between slop and runoff quantity was showed visibly when slop was above 42 degrees. Peak runoff could be affected by characteristic width of sub-catchment.

Flood control strategy in waibakul city, central sumba, Indonesia

Waibakul City, Central Sumba Regency, East Nusa Tenggara Province, Indonesia is affected by floods every year that comes from overflow of drainage channels. The area of Waibakul is 76, 44 km^2 and dominated by agricultural land. The drainage system is incorporated into the irrigation system, thus forming a complex network of channels. The topography of the area is very flat, with slope (0 to 3) % reaching 78.56% and forming natural basins that are used as rainwater catchment reservoirs. The results of evaluation show that the majority of channel capacity is not roportional to the burden that must be discharged. The reservoir performance is not maximal because the water discharge system only relies on natural water absorption into the soil, so if there is a successive rain then the reservoir is full thus the reservoir control capacity becomes very small. The recommendation for flood control strategies are: (1). Divide the catchment area into sub-catchment areas based on the drainage service area, so the problems can be more easily solved and completed gradually. (2). Increase the capacity of multiple channels. (3). infiltration wells as a means of reservoir water drainage.(4). Control the burden of flood discharge to the office area by making a shotcut. (5). Control the flood water level in rivers that is crossing central office area by making long storage with spillway.

Determination of subcatchment and watershed boundaries in a complex and highly urbanized landscape

AbstractUrban development significantly alters the landscape by introducing widespread impervious surfaces, which quickly convey surface run‐off to streams via stormwater sewer networks, resulting in “flashy” hydrological responses. Here, we present the inadequacies of using raster‐based digital elevation models and flow‐direction algorithms to delineate large and highly urbanized watersheds and propose an alternative approach that accounts for the influence of anthropogenically modified land cover. We use a semi‐automated approach that incorporates conventional drainage networks into overland flow paths and define the maximal run‐off contributing area. In this approach, stormwater pipes are clustered according to their slope attributes, which define flow direction. Land areas drained by each cluster and contributing (or exporting) flow to a topographically delineated catchment were determined. These land masses were subsequently added or removed from the catchment, modifying both the shape and the size. Our results in a highly urbanized Toronto, Canada, area watershed indicate a moderate net increase in the directly connected watershed area by 3% relative to a topographically forced method; however, differences across three smaller scale subcatchments are greater. Compared to topographic delineation, the directly connected watershed areas of both the upper and middle subcatchments decrease by 5% and 8%, respectively, whereas the lower subcatchment area increases by 15%. This is directly related to subsurface storm sewer pipes that cross topographic boundaries. When directly connected subcatchment area is plotted against total streamflow and flashiness indices using this method, the coefficients of variation are greater (0.93 to 0.97) compared to the use of digital elevation model‐derived subcatchment areas (0.78 to 0.85). The accurate identification of watershed and subcatchment boundaries should incorporate ancillary data such as stormwater sewer networks and retention basin drainage areas to reduce water budget errors in urban systems.

Land Use Change Assessment and Water Quality of Ephemeral Ponds for Irrigation in the North West Province, South Africa.

In the semi-arid environments of the North West province of South Africa the amount, timing, and distribution of rainfall is irregular, while water accessibility is a key factor in production. In line with this, a study was conducted to assess the impact of land use change on water quality and water depth within the sub-catchment areas of ephemeral ponds. To determine land use dynamics, 2004 and 2013 Landsat images were classified using maximum likelihood algorithm. Pond water quality was analysed for physical, chemical, and microbiological parameters using standard the American Public Health Association (APHA) methods. Multiple linear regression models were computed to determine relationships between land use changes and water quality parameters. Results revealed a reduction in grass cover, whereas built-up areas increased at the expense of bare land. All the values for the physical characteristics were higher than the recommended Department of Water Affairs (DWAF) and Food and Agriculture Organisation (FAO) limits, but chemical parameters, except cadmium, were within limits. Regression showed that bare areas have a positive effect on Escherichia coli (E. coli) in ephemeral pond water. The study highlights the suitability of pond water for irrigation to increase crop production and the effects of land use changes on ecosystems as critical for proper catchment planning, water resource management, and food security.

Does hillslope trenching enhance groundwater recharge and baseflow in the Peruvian Andes?

AbstractAs Andean glaciers rapidly retreat due to climate change, the balance of groundwater and glacial meltwater contributions to stream discharge in tropical, proglacial watersheds will change, potentially increasing vulnerability of water resources. The Shullcas River Watershed, near Huancayo, Peru, is fed only partly by the rapidly receding Huaytapallana glaciers (<20% of dry season flow). To potentially increase recharge and therefore increase groundwater derived baseflow, the government and not‐for‐profit organizations have installed trenches along large swaths of hillslope in the Shullcas Watershed. Our study focuses on a nonglacierized subcatchment of the Shullcas River Watershed and has 2 objectives: (a) create a model of the Shullcas groundwater system and assess the controls on stream discharge and (b) investigate the impact of the infiltration trenches on recharge and baseflow. We first collected hydrologic data from the field including a year‐long hydrograph (2015–2016), meteorological data (2011–2016), and infiltration measurements. We use a recharge model to evaluate the impact of trenched hillslopes on infiltration and runoff processes. Finally, we use a 3‐dimensional groundwater model, calibrated to the measured dry season baseflow, to determine the impact of trenching on the catchment. Simulations show that trenched hillslopes receive approximately 3.5% more recharge, relative to precipitation, compared with unaltered hillslopes. The groundwater model indicates that because the groundwater flow system is fast and shallow, incorporating trenched hillslopes (~2% of study subcatchment area) only slightly increases baseflow in the dry season. Furthermore, the location of trenching is an important consideration: Trenching higher in the catchment (further from the river) and in flatter terrain provides more baseflow during the dry season. The results of this study may have important implications for Andean landscape management and water resources.

Supply and Demand for Water Use by New Forest Plantations: A Market to Balance Increasing Upstream Water Use with Downstream Community, Industry and Environmental Use?

This study examines the use of water by existing downstream entitlement holders and their possible market interactions with upstream interests in new forestry plantations in the case of the Macquarie River Catchment, NSW. Demand for offset water to allow upstream plantation establishment is estimated as a function of tree product value and direct and opportunity costs in six sub-catchment areas with different rainfalls and locations with respect to urban and other high security water users (UHS). This upstream demand is aggregated with downstream demand for water. The aggregate supply of downstream water entitlements is posited in terms of marginal values to each of three sectors [stock & domestic (SD downstream losses, not counting damages to the wetlands, are $233M and $236M (summing the IRR and SD further, uncompensated losses of 154 and 156 GL in annual river flow would be suffered by the wetlands. With the requirement to purchase water for establishing new tree plantations, upstream surpluses are projected to be $192M and $220M in the FRESH and SALTY cases, respectively, while downstream sums of IRR and S&D surpluses are $138M and $151M, given 90 and 97 GL of water traded upstream with no damages to the wetlands. Greater surpluses in the hypothetical SALTY cases are due to subsidies paid by UHS for tree planting to reduce water yields from the very salty sub-catchment, thereby lowering river salinity to acceptable levels for domestic use. Although sale of downstream water entitlements may just balance reductions in river flow due to new tree plantations, water delivery efficiency may be reduced and overhead costs increased for those not selling entitlements. Our analysis has not counted these costs.

Assessment of Dissolved Ions and Microbial Coliform in Water from Selected Sites of the Upper Athi River Sub-Catchment Area, Kenya.

Assessment of Dissolved Ions and Microbial Coliform in Water from Selected Sites of the Upper Athi River Sub-Catchment Area, Kenya.

Correlating pattern of river discharge with degree of urbanization in sub-catchments of River Asa in Ilorin, Nigeria

The study examined the hydrological response pattern of urbanized streams to landuse in sub-catchment areas of River Asa in Ilorin, Nigeria. Data for the study were collected directly from the field over a period of one hydrological year. Rainfall data were collected in each basin using a standard rain gauge of 20cm orifice while basin discharge was computed from a rating equation generated from stage readings on staff gauge mounted at the outlet of each of the study basin. Landuse map of the study area was prepared from satellite imagery obtained from Regional Centre for Training in Aerospace Survey (RECTAS), Obafemi Awolowo University, Ile-Ife. Result obtained indicates that runoff discharge in all the studied basins reflects closely the rainfall pattern with periods of peak discharge coinciding with periods of heavy rainfall. The study further reveals that basin landuse characteristics have profound influence on pattern of river discharge. Based on the result obtained, the study recommends a number of options to efficient basin management in the city. Keywords: Pattern, Discharge, Landuse, Urbanization, Sub-catchment