Reconnaissance survey

The fieldwork started with a reconnaissance survey on the 17^th of June, 2012 to familiarise with the environment, identify the catchment boundaries and to assess sites delineated during the desk study to see how feasible they were for the fieldwork.

3.4.1. Site selection

Three sites or areas were chosen for the fieldwork as shown in Figure 3.4 due to a number of factors. The sites are Dansadau, Ribah and Fokku areas with their surrounding environment. The factors considered in choosing these sites are:

i. Diverse landscape features

The landscape features in the area chosen for fieldwork are diverse and spatially distributed. The choice of these regions will give a good coverage of various natural features within the catchment such as different mountains, sealed land surfaces, numerous rivers and streams, dense and light forests and cultivated lands. The mountainous landscape around Dansadau forms the origin of river Ka; the largest tributary to the river Ka originates in the highland subcatchments around Ribah area;

while the Fokku site is where the river gauge station is located close to the boundary between the basement complex and the sedimentary basin

ii. Accessibility

The presence of access roads to the three important towns of Dansadau, Ribah and Fokku within the catchment area and the river Ka has influenced the choice of these sites for the fieldwork. Because the research is looking at hydrological processes, much of the fieldwork is going to be conducted during the rainy season. The rocky nature and dense vegetation especially during the rainy season makes some part of the catchment inaccessible to motor vehicles. There is also the need to choose an area where adequate accommodation is available. The fieldwork sites are all located within less than 60 miles to big cities like Gusau, Zuru and Jega (see Figure 3.4) where hotel

iii. Security

Insecurity is one of the major factors that led to the choice of these sites. There are lots of armed robbery gangs and also wild life living in the forest that may endanger the life, health and properties of the researcher during the fieldwork. In the alternative, the forest areas used in this research are closer to the main road (within 1 km distance).

Figure 3.4: The location of fieldwork sites (dotted lines) within the River Ka catchment

During the reconnaissance, visits were made to the district heads where formal introductions and the mission statement were presented (Figure 3.5). A short structured interview (see Appendix A) with the district heads was conducted in order to obtain a brief history of the towns, the inhabitants and their activities, the water sources and the nature of soils.

Semi-structured interviews were also conducted with local people selected by the district heads, who were considered to have good knowledge of the local environment.

Some of them also acted as a guide to specific sites during the fieldwork. The questions asked in the interview are purposely to tap the local people’s knowledge to be used, in addition to the knowledge from literature, for interpreting the hydrological processes and modelling.

Figure 3.5: District head of (1) Fokku and (2) Dansadau with the researcher after the fieldwork interview

The general questions asked during the semi-structured interview (not in sequential order) include the following:

 The time of onset and stoppage of rainfall in the area.

 The type of crops grown and duration to harvest, and whether they obtain good yields of their crops every year.

 Duration of moisture holding in the soil after rainfall, and whether floods occur and when.

 Duration that water stays on the surface after rainfall and where the water goes afterward.

 Sources of water supply for domestic and other uses during rainy or dry season and the depth of hand dug wells in the area.

In conclusion, site visits and observations were made to some landscapes such as the river Ka, the surrounding hills, sealed land surfaces and some forest areas.

3.4.2. The Fieldwork Processes

Fieldwork was conducted in the three selected areas as described in section 3.3 from 17^th June – 30^th August 2012. Visitation to the three sites was dependent on the timing of likely occurrence of rainfall within the fieldwork period. The fieldwork conducted involved measurement of water table depth in dug wells and boreholes; soil type and depth identification; observation of surface runoff processes (such as the origin, flow paths and destination) during and after rainfall; vegetation / crop types, cover and growth behaviour. Other aspects recorded included water sources and location in towns and surrounding environment, available streams, lakes or ponds and identification of hard rock types (fractured or non- fractured) and their runoff behaviour after rainfall.

The fieldwork conducted has uncovered many issues controlling the hydrological processes within the basement complex region. It was apparent that the actual hydrological processes are much more complex than earlier thought or reported in literatures. After the fieldwork, the initial conceptual model given in Figure 3.3 was revisited and refined to reflect the new understanding of hydrological processes within the basement complex region. This resulted in developing different individual conceptual models, each representing a different hydrological response after rainfall within the study area. The different conceptual models (named as landscape models) are fully discussed in chapter four.