Spatial Distribution of Soil Hydrological Properties in the Kilombero Floodplain, Tanzania

Abstract

Analysis and interpretation of soil properties dynamics is a keystone in understanding the hydrologic responses and yield potential of floodplain wetlands. This study characterizes the distribution and spatial trends of selected soil physical properties in the Kilombero floodplain, Tanzania. A total of 76 composite soil samples were taken from 0 to 20 cm and 20 to 40 cm depth in a regular grid design across three hydrological zones, related to flooding intensity defined as fringe, middle, and riparian during the rainy season of 2015. The samples were analyzed for soil texture, bulk density, organic carbon, and saturated hydraulic conductivity. Seasonal soil moisture content was monitored at depths of 10, 20, 30, and 40 cm, using 17 frequency domain reflectometry profile probes type PR2, installed at each hydrological zone for 18 months (March 2015-August 2016). Data were subjected to classical statistical and geostatistical analyses. Results showed significant (p < 0.05) differences in bulk density, texture, soil organic carbon (SOC), and saturated hydraulic conductivity (K sat ) across the hydrological zones. Bulk density showed a clear increasing trend towards the fringe zone. Mean K sat was highest at the riparian zone (69.15 cm·d −1 ), and clay was higher in the riparian (20.3%) and middle (28.7%) zones, whereas fringe had the highest percentage of sand (33.7-35.9%). Geostatistical spatial results indicated that bulk density, silt, and SOC at 0-20 cm had intermediate dependence, whereas other soil properties at both depths had high spatial dependence. Soil moisture content showed a significant (p < 0.05) difference across the hydrological zones. The riparian zone retained the highest soil moisture content compared to the middle and fringe zone. The temporal soil moisture pattern corresponded to rainfall seasonality and at the riparian zone, soil moisture exhibited a convex shape of sloping curve, whereas a concave sloping curve for topsoil and for the middle zone at the subsoil was observed during the start of the dry season. Our results are seen to contribute to a better understanding of the spatial distribution of soil properties and as a reference for soil and water management planning in the floodplain.

Agricultural potentials of floodplain soils with contrasting parent material in Cross River State, Nigeria

“…The difference in particle size distributions between coastal plain sand and basement complex rock were not statistically significant as depicted by the t-test values (t = -0.061, df = 9, p > 0.05), (t = -0.235, df = 9, p >0.05), (t = 0.394; df = 9, p > 0.05) for sand, silt and clay, respectively (Table 3). This result contrast the report of Esu et al (2014) and Yakubu and Ojanuga (2000) that topography, soil depth and parent materials are attributable to differences in pattern of soil distribution and properties of soil over landscape but corroborates the report of Reddy and DeLaune (2008) and Daniel et al (2017) that in all floodplain soils, fresh materials are frequently added through depositions and are characterized with a mixture of clay, silts, sand, which may perhaps have similar properties. The texture observed irrespective of depth and parent materials can be favourable for agricultural cultivation.…”

“…Despite the over-whelming acceptance of floodplain soils for agriculture, those located within Obufa Esuk Orok, Calabar and Awi, Akamkpa have little been studied and are currently under-utilized and their soil qualities and agricultural potential to support crop growth and yield is unknown. Although, wide variations in nutrient contents exist between upland soils developed on different parent materials within the same climatic condition and geographical location in Cross River State (Gbadegesin et al, 2011, Afu et al, 2017 and elsewhere, but it is not clear if there would be similar significant differences in nutrient contents of floodplain soils developed on different parent material within the same environmental condition, bearing in mind that in all floodplain soils, fresh materials are frequently added through depositions and are characterized with a mixture of clay, silts, sands, and organic materials, and therefore, would both be considered to have high and similar soil fertility status and hence, potential for crop production (Reddy and DeLaune, 2008;Daniel et al, 2017). Thus, there is a need for testing the floodplain soils located on soils of two parent materials in Cross River State to find out if there are differences in soil properties between the two soils and to avoid a situation whereby a wrong soil management practice is imposed upon the soil in the event of allocating it for crop cultivation.…”

Hydrological Modeling in Data-Scarce Catchments: The Kilombero Floodplain in Tanzania

“…Yawson et al [24] applied lumped models and linear transfer approaches, while Lyon et al [25] investigated spatio-temporal drainage patterns. Subcatchments of the Kilombero Catchment were analyzed by Burghof et al [26], Koutsouris et al [27], and Daniel et al [28], by developing a conceptual model, setting up an HBV (Hydrologiska Byråns Vattenavdelning) light model [29] for two subcatchments and by analyzing soil hydrological properties in a floodplain transect. These studies investigated water-related relationships within the Kilombero Catchment, giving either a detailed insight into specific subcatchments without considering the entire catchment [25][26][27]-or the entire catchment was analyzed, but without considering the spatial heterogeneity [24].…”

Characterizing Total Phosphorus in Current and Geologic Utah Lake Sediments: Implications for Water Quality Management Issues

“…We used common statistical and spatial analysis tests [44][45][46][47][48][49]. We performed a chi-square test to determine the likelihood that data in the different lake sections came from difference populations.…”