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Inland valley agro-ecosystems which are a category of wetlands have potential for sustainable crop production relative to uplands. A major challenge to their utilisation in the study area is their heterogeneity in hydrology, morphology, soil types and agro-economy. The study assessed the surface water quality of three typologies of the agro-ecosystems-amphitheatre-like valley-heads (Am), valley-side (VS), and low depression (LD)-for cropping. Surface water of six sites were sampled during the wet and dry seasons. The physicochemical properties and metal concentrations of the samples were analysed. Descriptive statistics and water quality indices were used to assess the suitability of the waters of the agro-ecosystems for cropping. Results showed that the valleys have neutral to slightly alkaline waters. Values of physicochemical parameters are generally within the acceptable range for cropping. The concentration of major cations varied across the inland valley types, but exhibited similar characteristics within each valley. The dominance of the major cations is in the order of Na [ Ca [ K [ Mg. ANOVA results indicated that there is no significant difference in the concentration of heavy metals across the valleys (F = 2.044, p = 0.138, a = 0.05). Generally, most of the physicochemical parameters and trace metals have low concentrations and are non-toxic to plants. Values of water quality indices (sodium adsorption ratio, soluble sodium percentage, total dissolved solids and permeability index) indicated that the concentrations of minerals in waters across the valley typologies are generally within permissible limits for cropping.

The potential use of inland valley ecosystems (a category of wetlands) for cropping has not been fully exploited due to their heterogeneity in hydrology, morphology, soil types and agro-economy. The study employed the hydro-period approach to investigate the dynamics of surface waters of six inland valley sites. Hydrographs and hydro-periods of the sites were determined using water-level fluctuation data collected using staff gages. Results show that water level rose gradually from the beginning of the rain season, peaked at the end of the season, and receded gradually until the hydrological peak of dry season in amphitheatre and valley-side valley types. In the low depression valleys, the plots indicate a more instantaneous response to rainfall events with little groundwater flow. The work concluded that amphitheatre and valley-side valleys types are perennial with high base flows and low flow variability, and hence should be suitable for year-round cropping with little or no application of irrigation. On the other hand, the stage-duration curves of the depression valleys are characteristics of seasonal streams occurring in low-sloped topography with largely rain-caused floods, low base flow, and high flow variability. Application of irrigation may be required for dry season cropping in these valleys.