QUANTITATIVE AND QUALITATIVE EVIDENCE OF ANTHROPOGENIC FINGERPRINT IN FLOODING IN TARABA STATE OF NIGERIA

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INTRODUCTION
Anthropogenic activities have been reported as major causes of climate change. Human activities since the industrial revolution have increased the atmospheric concentration of various greenhouse gasses, leading to increased air pollution from CO2, methane, troposphere ozone, CFCs and nitrous oxide. Predrag and Slobodan, 2007, had long asserted that changes in the earth's climatic system can disrupt the delicate balance of the hydrologic cycle and can eventually lead to increased occurrence of extreme events (such as floods, droughts, heat waves, summer and ice storms. In the same vein, increase in population growth and the resultant rise in the need for food production. Researchers (McKenzie and Williams, 2015;Parvin, et al., 2019) agreed that aggressive anthropogenic activities greatly influence land use and land cover and consequently climate change.
Taraba state is an agrarian community. The state is endowed with natural resources; vast lands, water resources, animal resources and human resources (Adelalu et al.2020b). More than 70 percent of the inhabitants derive their livelihood directly or indirectly from agriculture or agricultural related business. In the face of climate change, the means of livelihood of the inhabitants who are mostly farmers has dwindled (Adelalu et al.2020a).
Climate change has begun to create havoc in the state (Oruonye, 2012a). The increased adverse impact of the flood is expected on the physical infrastructure, human health, natural resources, economic activities, and the environment (Plate I-V). This can be compounded with the increase in the deforestation, general burning in the farming season, overgrazing and the recent mass lumbering business of rose wood in the southern part of the state. IMF (1993) asserted that poverty and the environment are linked because the poor in the community are more likely to resort to activities that can degrade the environment. More lands could be denuded and resultant runoff could lead to flooding.
Since its creation in 1991, Taraba state has experienced several socio-economic and natural of which rural farmers are the most vulnerable. The vulnerability surges in the face of the incessant crisis in the region. Flooding is next to religious and tribal crisis in the context of economic back pedaling of the government effort to curb poverty in the state. Amidst plenty, food insecurity and incessant crisis ravage the government efforts to sustainable agricultural and economic development. The current COVID-19 pandemic may reduce the government's responsiveness and commitment to the nationwide effective monitoring, adaptation and mitigation measures to climate change in the country.
Previous studies on the flooding issue in the state concentrated on the farmers perception and adaptation to climate change (Adebayo and Orunoye, 2013), awareness of the effect of climate change among students of tertiary institution in Jalingo (Oruonye, 2011), Land use and its implication on natural environment of Donga (Adelalu and Zemba, 2017).To provide comprehensive flood control/prevention plans or policies particularly in areas prone to floods, there is need for state wide study that analyze the interaction between climatic factors and the runoff. New instruments, techniques and methods have been developed to capture rainfall and hydrological processes at high resolution (Elena et al., 2017). Quantitative and qualitative device to investigate the physical environment influence on the functioning and development of societies are no longer wanting. A quantitative and qualitative knowledge of the spatio-temporal changes in rainfall and temperature and the resultant river flows is crucial in the study area. This informs the government on the right policy direction and approaches to be pursued. This is particularly important to Plate 5: Unlawful settlements along water ways of Lamurde river

AIM AND OBJECTIVES
The aim of this study was to analyze the spatial and temporal characteristics of the rainfall and categorize the land use type over the study area with a view to determining their influence on flood vulnerability along the major tributaries of River Benue in Taraba State. It evaluates rainfall variability and the influence on runoff (flood) in the state using geospatial and statistical instruments.

STUDY AREA
The study area lies between latitude 6° 30' and 9° 30' North of equator and between Longitude 9° 00' and 12° 00' East of the Greenwich Meridian. It has a total land area of about 60,291km 2 (National Statistic Office, 2018). The land area has three major tributaries to River Benue: River Lamurde, River Taraba and River Donga (Figure 1).
There exist twenty-two sub-basins in the study area and these sub-basins network with these three major rivers and drained a total area of about 44,359 km 2 having perimeter of about 1522km (Adelalu et al.2020a). Inter-tropical Discontinuity (ITD) determines the climate of the study area which is marked by dry and rainy seasons.
Temperature figure typifies African Savanna features (Adebayo and Tukur, 1999) with an average minimum temperature of 15.2 o C, while the average maximum temperature is 39.7 o C. The hottest months are March and April with maxima temperature of 34.5 o C. Rainfall usually starts around April-May and ends around September-October.
Heavy thunder storms occur in major parts of the state around July and August. It is not also uncommon to have the peak of rainfall at this period. This may not herald flooding if the system is not reimbursed by water released from Lagdo dam, consequently causing major floods and inundation at about three-quarter of the sixteen local government areas. Crop production, stock raising and animal husbandry form the mainstay of the people. However, surge in population especially after the North-east insurgence has been changing the distribution of agricultural land use. Obviously now, farmers are withdrawing from the farmlands to intensive hinterland farming close to houses and drains (Adelalu et al.2020b). This is probably not unconnected with the farmer-pastoralists conflicts in the region. The vegetation type of the study area has been adversely affected by human activities leading to the clearcutting of trees in many parts of the area. Artificial vegetation and few economic trees have replaced the natural vegetation especially as we transverse the northern part of the study area. In the past, the local people usually collect fuel wood right at their backyard but today, they travel a long distance to collect fuel wood for their domestic energy (Oruonye, 2012a).

METHODOLOGY
The data used for this study include satellite images and the mean annual rainfall and runoff of Taraba. The satellite images of the state were derived from United States Geological Survey Explorer. Image sampling was carried out to determine training sample sets during field checks. For date, source and data format see Table 1. Relationship between rainfall and river flow in Taraba over the years in the study area were determined using thirty-five years of rainfall data. This is available for use in all the study basins except for River Donga, however with adequate hydrological data from stations in three places (Tepkwar, Gindin-Doruwa and Donga). Little data processing was made to augment for missing data in rainfall by using the rainfall simulation of the area downloaded from U.S. Geological Survey (USGS) Word Climate Database with the help of ERDAS 9.0 version. The rainfall-runoff relationship of the catchment was established and the rainfall-runoff regression line generated. From this regression equation, fixing of the missing data was made. To determine the land use/land cover type. Training site was chosen to represent land use classes such as vegetation, built up area, bare land and water body. Classifications were limited to these variables because these have been established to have linkage to flooding hazard in the study area.
Supervised image classification technique was employed. With this technique, samples of the different features on the image were given pixel depicting a given land use/land cover type. Atmospheric correction was applied to remove the dust and haze effect from the image by using the dark-object subtraction method (Chavez, 2006). The false color composite image was classified using Maximum Likelihood Classification Algorithm. The Maximum Likelihood Classifier assumes that a pixel has certain probability belonging to a particular class. The results from the analysis are presented in the form of tables and map. To assess the inhabitants' level of awareness and cause of flood hazard in the area, questionnaire was designed to capture the bio-data and socioeconomic characteristics of the respondents which include age, sex, marital status, occupation, level of education, and length of stay in the area. The other part of the questionnaire had connection to environmental use and its interrelation with flooding. Purposeful sampling method was used to select sampled wards base on the endemic status of the councils. For instance, Donga has 10 wards but GyataAure and Fada were selected because these two wards were more endemic in times of flooding than any other wards. Similar reason was the bases of selection of wards along river Taraba and river Lamurde. Random sampling was used in the administration of questionnaire and sample size as specified in Table 2.  vegetation cover, which is more than 50% of the basin area, generally one would have expected low occurrence of flooding in the study area however the reverse was the case.           insignificant. Adjusted R-Square is 0.023 (Table 9b). This means the independent variable only account for 2.3 % effect on the dependent variable. This is the percentage variation in runoff that can be accounted for by the regression model. This indicates that the predictor (rainfall) does not significantly predict runoff.      that the proportion of variation in dependent variable (runoff) explained by independent (rainfall) are 1.9%, 5%, 23.6% respectively. So, causes of flooding cannot be attributed to rainfall.

COMMUNITIES' ASSESSMENT OF CLIMATE CHANGE: CAUSES AND IMPACT
The researchers believed that those inhabitants especially long-term residents could have a reasonable idea of the extent of flooding in the locality. The questions in Table X sought to ascertain how long the respondents have lived in the area. For instance, more than 60% of the respondents in Lamurde had been in the study area for more than 20 years. In river Taraba catchment area, close to 70% of the respondents had been in the study area for more than 20 years while in Fada and Gyata Aure close to 90% of the respondents had been in the study area for more than 20 years. It is assumed that they have a better chance of relating the story better.
Regarding the incessant flooding in the Lamurde catchment area, floodplain encroachment and increase in rainfall intensity have been identified as the culprits. Encroachment accounts for 34% while about 26% of the respondents support the fact that rainfall intensity increase is the causative agent. Land use change, in the area of increase in deforestation through logging and constructions account for 20% while about 4% of the respondents support the fact that the low land terrain is the cause of the flooding. Others factors outside the listed cause in the questionnaire identified by respondents include disposal of waste dump in channels and drainages. 16% of the respondents are in this category (Table 11).
In the lower latitude, at river Taraba catchment area, majority are in the category of other causes different from the listed in the questionnaire. General perception of the respondents who have lived more than 20 years and above in locality affirmed that excess of water from the Lagdo Dam is responsible for the yearly flooding of the area. About 51% of the respondents are attestants to this (Table 11). Floodplain encroachment accounts for 39% while about 4% of the respondents support the fact that the low land terrain is the cause of the flooding. Only 18% associate increase in rainfall intensity to flooding. Number one on the list on the general perception of the respondents who have lived more than 20 years and above in Fada and Gyata Aure localities affirmed that there has been increase in the rainfall intensity. About 47% of the respondents are attestants to this (Table 11). This corroborates the findings of Oyatayo et al., 2015. However, up north of the study area, in Lamurde and Taraba basin, according to preliminary report (Adebayo, 2012), rainfall have been decreasing.
Also, in Fada and Gyata Aure floodplain encroachment accounts for 37% while about 8% of the respondents support the fact that the low land terrain is the cause of the flooding. Even though only 8% of the respondents adduced flooding to change in land use and land cover, the analyzed imageries by (Gabriel and Audu, 2017) show that between the spaces of 16 years, (2000-1016) the present built up area is fifth times of the capture in the year 2000 and that 16% of the vegetation cover has disappeared for other use.
The responses in Table 12 (Table 12). indicate that the proportion of variation in dependent variable (runoff) explained by independent (rainfall) are 1.9%, 5%, 23.6% respectively. Therefore, causes of flooding cannot be solely attributed to rainfall. Though, climate change alters our physical veracities, the problem of yearly flooding is more a human than a natural one in Taraba State. Various anthropogenic activities such as agriculture, deforestation, irrigations, dam construction have taken place especially along the river banks of the major tributaries to river Benue in the state. The cumulative effect of these human activities (deforestation, encroachment, artisan mining etc.) together with natural factors in some parts of the study area has led to environmental degradation in the state which seems abetting incessant flooding.

RECOMMENDATIONS
The region's status is vulnerable to climate change no doubt. However, the vulnerability has alliance with the Land use and land cover change. The present government effort in the channelization of the drainage is commendable.
There is need for farmers to adopt 'farm forest' method of farming system, holistic logging and infrastructural development by respective stakeholders. Farm forest will not only checkmate adverse effect of flooding but serve as windbreak and source of additional revenue apart from adding nutrients to the soil. Tree planting campaign and implementation in the state by some concerned NGO was not sustained in the state. Many trees that were planted were eaten up by goats or dried up by scorching radiation of the sun. Nonchalant attitude of officers designated in some government areas and house landlords' responsibilities to monitor and provide water for the trees planted to their frontage need to be addressed. There is need for a platform e.g. office of Climate Change and Land Reform and the office should be saddled with the responsibility to disseminate and also to create more awareness on climate change, danger of flood plain encroachment.

CONFLICT OF INTEREST
The authors declare that we have no conflict of interest as authors.