The spatial and temporal characterisation of flooding within the floodplain wetland of the Nyl River, Limpopo Province, South Africa

Abstract

The inundated area of a wetland is characterised by annual and interannual variability. This paper presents remotely-sensed imagery in order to better understand the spatial and temporal patterns of flooding within the floodplain wetland of the Nyl River, Limpopo Province. A detailed understanding of the hydrological characteristics of these flood events is essential in order to develop sustainable ecological and hydrological management plans for the area. From the results, flooding is shown to occur in 2 distinct phases. The initial phase is characterised by water ponding on the floodplain. The later phase is characterised by the input of water from tributaries to the north (e.g. Andriesspruit and Tobiasspriut) and southwest (e.g. Klein Nyl and Groot Nyl). This distinction may relate to the increasingly widespread practice of agricultural irrigation within adjacent tributary catchments. The methodology described in this study could yield valuable results when applied to other wetland systems in southern Africa.

A Review of Coupled Hydrologic-Hydraulic Models for Floodplain Assessments in Africa: Opportunities and Challenges for Floodplain Wetland Management

“…Ref. [31] emphasis that detailed understanding of the hydrological and hydraulic characteristics of wetland hydrology is essential in order to develop sustainable ecological and hydrological management plans. The ecological status of the floodplain may be threatened by the increasing development of upstream catchments, as this affects the amount and timing of water delivered to the floodplain.…”

Rainfall Trend and Its Relationship with Normalized Difference Vegetation Index in a Restored Semi-Arid Wetland of South Africa

“…The wetland's ability to provide groundwater recharge throughout the year makes it valuable and prompts the need for its conservation [45]. Rowberry et al [52] note that the ecological status of the freshwater wetland has The floodplain houses over 100 aquatic bird species, 57 of which breed in this wetland. This makes it an important nesting and feeding site for migratory birds and several endangered species.…”

Visualisation of flooding along an unvegetated, ephemeral river using Google Earth Engine: Implications for assessment of channel-floodplain dynamics in a time of rapid environmental change

“…Owing to the difficulties of obtaining field measurements or observations of large or extreme hydrological events in drylands, particular interest has been turning to the use of remote sensing techniques to visualise flooding extent, flooding patterns, and channel-floodplain dynamics along dryland rivers (e.g. Gumbricht et al, 2004;Ip et al, 2006;Milzow et al, 2009;Rowberry et al, 2011;Li et al, 2014aLi et al, , b, 2018Thito et al, 2016;Milan et al, 2018;Heritage et al, 2019). Many previous studies have focused on flood mapping from one or a few satellite images captured during or after floods, but these images may contain limited information due to low spectral and temporal resolution (e.g.…”

“…In addition, in some dryland regions, obtaining cloud-free imagery during or immediately following peak flood events is notoriously difficult (e.g. Rowberry et al, 2011;Li et al, 2018), and this problem is compounded when attempting to undertake multiple-year mapping and monitoring. Therefore, visualisations of flood extents and patterns remain particularly poorly developed in many drylands.…”