COMPARATIVE ANALYSIS OF THE SPATIAL AND TEMPORAL VARIATIONS IN HYDROLOGICAL PARAMETERS AT KAINJI AND SHIRORO DAMS, NIGER STATE, NIGERIA

ABSTRACT

Climate variability has been one of the major issues of the 21st century. The idea is to understand the differences in the climatic conditions and long-term catchment regimes using mean monthly seasonality indices and to explore the differences in the hydrological parameters at the long-term event scale. This comparatively analyze of spatial temporal variations in hydrological parameters at Kainji and Shiroro Dams in Niger State towards achieving a better future plan in the area. Quantitative and qualitative research approach was used, geospatial techniques were used to analysis the landuse pattern of the dams areas.  Landsat satellite imagery was also acquired for 1997 to 2017. The imagery was subjected to digital process and five landuse classes were generated. Mann-Kendall test and Sen’s slope test on the monthly coefficient of variation for rainfall, reservoir inflow, reservoir elevation. The results show rainfall deviations increased between 1998 and 1999. On decadal basis, the years 1998, 1999, 2004, and 2006 have positive rainfall deviations while the remaining years have negative and least rainfall deviations. It was also revealing that evaporation deviation was increased in the years 1995 but it reduced drastically between 1993 and 1994. The analyses revealed a negative trend, and a slight decrease in rainfall and it can be brought to conclusion that since evaporation and reservoir inflow has the greatest impact because increase evaporation will increase and there will be shortage of water in the dam. It recommended that operators optimize the release of water from Kainji dam and ensure continuous monitoring of changes in hydro metrological variables to provide early warning for effective performance of the dam and to protect the environment.

CHAPTER ONE

1.0                                                       INTRODUCTION

1.1 Background to the Study

Hydrology is the science of water which deals with the water of earth and its atmosphere. It is the study of occurrence, circulation, distribution, chemical and physical properties of all forms of water and also their reaction with the nature including human (Apalando, 2012). It is an important aspect for the living being including both human and the environment. It concerns with the water in streams, lakes, rainfall, snowfall, snow, ice on the land and even water occurring below the earth’s surface in the pores of the soil and rocks. Hydrological parameters such as precipitation, surface runoff, evapotranspiration, interception, infiltration, change in soil moisture, river flow, and change in groundwater storage are part of Earth’s dynamic ecosystem.

Climate and human induced changes on catchment hydrological processes are major concerns for scientists, water decision-makers, and politicians. Different scenarios of climate change and its impact on water balance directly and on ecological, chemical, and geomorphological processes indirectly are the main issues of many studies in the last ten years all over the world. Most of them were dealing with different climate scenarios and their impact on global ecosystem, water management, or economy. Global modelling with simulating global water cycle and in that context analysing hydrological extremes and water balance components is the most common approach, as Corzo Perez et al. (2011) stated (Corzo-Perez et al., 2011). Droughts are global hydrological phenomena found to increase in duration, area, and severity, according to Lloyd-Hughes et al. (2013). But validation of global models had to be done by observations on smaller scale, on the number of catchment areas of different characteristics, as it was studied by Stahl et al. (2010).

Climate change is the alteration in the temperature, rainfall, humidity, wind and seasons. It is the seasonal alteration of weather over an extended period due to global warming (Apalando, 2012). These alterations have an impact on surface water like a dam, rivers, agriculture production, and causes either flood or drought in the area. Globally, the effect of climate change has led to numerous issues in water resources like flooding and drought (Shen and Qiang, 2014). Rainfall is the only parameter that changes the reservoir inflow, reservoir elevation and turbine discharge in the dam (Shen and Qiang, 2014). These changes occur in space and time. Rainfall inconsistency in different locations over time causes counterpart runoff generation which affects water availability positively or negatively in the area (Warwade et al., 2018).  The rate of change of runoff has a critical effect on hydrological cycles and its variables. Runoff influenced by human activities such as land use and housing development at the upstream and climate change. Identification of the spatial and temporal variations caused by rainfall and runoff is essential for water resources planning and management (Lee and Kim, 2017).

Climate variability has been one of the major issues of the 21st century. In fact, its importance keeps on increasing with the realization that its impacts cut across all sectors of a country’s economy. Hence it should not only be looked at just as an environmental issue but also a developmental issue. Presently the scientific consensus on climate change is that human activity is very likely the cause for the increase in global average temperatures over the past several decades (IPCC, 2001). The increase in the world’s population over the last century, complemented by the rise in the standards of living, has resulted in a rise in the demand for energy. According to John and James (2011); Adegbehin, et al., (2016) Scientists predict that the global population will swell to over 10 billion by 2050. The impacts of climate variability and change are real and would continue to affect sensitive sectors of the global economy. Productive sectors such as agriculture, water, health, energy, and transport among others bear the brunt of these variability and change in the world’s climate. Even though the entire globe will experience the impacts of these changes, the more severe impacts will be felt in low latitude developing countries where several non-climatic stressors are already at play (IPCC, 2007a). Sub-Saharan Africa continues to exhibit vulnerability to variability and change in climatic parameters such as temperature, rainfall and extreme events resulting from both anthropogenic climate change and natural variability. The principal known source of tropical climate variability is the El Niño-Southern Oscillation [ENSO] (Collins et al., 2010; Camberlin et al., 2001).

The Intergovernmental Panel on Climate Change (2007) reported that rainfall variability on spatial and temporal had increased globally. These variations affect dam variables such as reservoir elevation, reservoir inflow, and turbine discharge. Furthermore, the disposition of spatial and temporal rainfall variability and others hydrological variables such as reservoir inflow, reservoir elevation, and turbine discharge were poorly understood (Cristiano et al, 2017).

The spatial temporal variations of hydrological characteristics are one of the key factors controlling the development and stability of natural ecosystems. From a hydrological perspective, spatial temporal analysis of runoff and precipitation is an appealing method for inferring flood generation mechanisms, which, in turn, supports other hydrological applications, such as hydrological regionalisation. Recently, the assessment of hydrological seasonality and regime stability has attracted a renewed interest, especially in connection with water resources management, engineering design and land cover and climate change assessment studies (Krasovskaia and Gottschalk, 2002; Krasovskaia et al., 2003; Bower et al., 2004; García and Mechoso, 2005).

Although, previous studies use weather radar to analyse the spatial and temporal variation and the outcome was poorly understood. Presently, numerous studies use multivariate statistics such as cluster, discriminant and Principal component  analysis and Mann Kendall test to analyse the spatial and temporal variation of hydrological variables. Shen and Qiang (2014) examined the spatial and temporal variation of annual precipitation in a river of the loess plateau in China and multivariate statistical methods, and Mann Kendall were used. Their results showed that there was two spatial pattern that increases in the northwest, a decrease in the southeast and an increase in the west and the decrease in the east. Javari (2016) examined the spatial-temporal variability of seasonal precipitation in Iran. This study used an annual time series procedure and spatial (GIS) method, and their results showed that the rainfall had two spatial patterns in the area.

Hence,  this  study will  comparatively analysis  the spatial  temporal  of  hydrological parameters of both Kainji and Shiroro dam within the context of ecosystem sustainability. The main idea is to understand the differences in the climatic conditions and long-term catchment regimes using mean monthly seasonality indices, and to explore the differences in the hydrological parameters at the long-term event scale. It is anticipated that the combination of both concepts within the framework of comparative hydrology may give an insight into the main hydrological processes in Kainji and Shiroro dams. The two hydrological dams have many common features with respect to runoff forcing and generation. Similar precipitation regimes exist in both areas (Tolulope, 2011).

1.2       Statement of the Research Problem

The overdependence on hydropower has exposed the country to the impacts of climate variability. One of the potential effects of variability in climate, especially reduction in the amount and deviation in the distribution of rainfall, is the possibility of changes to river flow and runoff which will affect energy supply from hydropower sources (Energy Commission & United Nations, 2012) Harrison et al., (2014). The existing hydropower capacity in Nigeria was built long before engineering and general public were aware of the impact of climate change on large infrastructure. Sudden climate variability has posed a dangerous threat in our poorly managed hydropower dam. Rising global temperatures will lead to an intensification of the hydrological cycle, resulting in drier dry seasons and wetter rainy seasons, and subsequently height and risks of more extreme and frequent floods. It will equally have significant impact on the availability and accessibility of water as well  as the quantity of water that is  available and  accessible. All  these factors highlighted will have an adverse impact on our hydropower dams. Therefore, periodic check on hydro climatic condition of our various dams is of serious concern, because failure of it will result to economic loss, and its attendant problems.

This study is purposely undertaken due to the frequent destruction of vegetation, farmlands and residential area downstream of Kainji and Shiroro dam. Biophysical impact analysis is necessary in order to reduce the impact of subsequent flooding event in the community. Government, although had already conducted many surveys to measure and assess flood damage, but the impact assessment at the micro-level based on community data, including the effect on the community hasn’t been done yet. No such studies attempted to link these destructions to emission of greenhouse gases whose increase in the negative environmental consequences of dam construction on inundation of terrestrial habitats, modification of hydrological regimes, and modification of aquatic habitats is thus, emphasized lead to climate change. Therefore, this study will be carried out to comparatively analysis the spatial and temporal variations in hydrological parameters of Kainji and Shiroro Dams in Niger State for effective sustainability of ecosystem.

1.3     Aim and Objectives of the Study

The aim of the study is to comparatively analyze the spatial and temporal variations in hydrological parameters at Kainji and Shiroro Dams in Niger State towards achieving a better future plan in the area. The specific objectives are to:

i.      examine the spatial-temporal characteristics of Kainji and Shiroro Dam;

ii.      examine the spatial variations of rainfall, reservoir inflow, reservoir elevation, evaporation and turbine discharge in Shiroro and Kainji dam.

iii.      compare the spatial variations on discharge as a function of human activities, climate change and land use patterns in the upstream areas of the selected dams

1.4     Research Questions

i.      What is the spatial-temporal characteristics of Kainji and Shiroro Dam;

ii.      What are the spatial variations of rainfall, reservoir inflow, reservoir elevation, evaporation and turbine discharge in Shiroro and Kainji dam?

iii.      Are there difference in spatial variations on discharge as a function of human activities, climate change and land use patterns in the upstream areas of the selected dams

1.5    Justification of the Study

The spatial and temporal distribution of hydrological variables such as rainfall, reservoir inflow, reservoir elevation and discharge are crucial in hydrology, water resource management, agriculture and irrigation under climate change. The noesis of the spatial and temporal variation of the reservoir inflow, reservoir elevation, and turbine discharge is essential for water resources planning and management. The knowledge of spatial and temporal changes of reservoir inflow, reservoir elevation, and turbine discharge will be used as an essential tool for quantifying the variations (Saraiva et al., 2015) and predicting future hydrological variables like reservoir inflow, reservoir elevation and turbine discharge under rainfall variability and climate change.

The significance of this research cannot be over emphasized, especially for the optimum result in saving lives and protection of properties in the long run. In the past, the spatial temporal of hydrological characteristics was analysed mainly in the context of flooding (Falkenmark & Chapman, 1989). The main idea was to study the character of hydrological processes and to identify regions with similar hydrological responses. There are numerous studies on the spatial temporal variations of the long-term mean monthly runoff regime (e.g. Lvovich, 1938; Pardé, 1947; Gottschalk, 1985; Haines et al., 1988; Arnell et al., 1993; Krasovskaia et al., 1994; Dettinger & Diaz, 2000; Bower et al., 2004; Johnston & Shmagin, 2008).   In many studies the hydrological regime is analysed over a single region (Pfaundler, 2001; Archer, 2003; Birsan et al., 2005; Assani et al., 2006; Molnar & Burlando, 2008; Petrow et al., 2007; Sauquet et al., 2008; Solin, 2008), but only a few studies compare two dams with large data sets to evaluate the seasonality across the boundaries of administrative units (Krasovskaia, 1995, 1996; Dettinger & Diaz, 2000; Krasovskaia & Gottschalk, 2002).   Therefore, this study will fill the gap by comparatively analysis two big dam (Kainji and Shiroro) in the context of their spatial temporal characteristics in hydrological parameters.

This study requires an understanding of the hydrological characteristics and its interaction with the spatial temporal variations of the catchment. Hence, for effective planning and application of water resources management, there should be a basis or a study that must expose the areas that need attention. In this regard, this study will provide the opportunity for well-structured spatial and temporal variation of hydrological parameters and offer a sound scientific analysis for a coordinated management and planning. This in turn will facilitates reasonable and equitable use of scarce and vulnerable water resources by all stakeholders. It is hoped that the results from this study will have significant implications on the current and future land and water resources management in Nigeria.

1.6    Scope of the Study

The focal point of this study covers Kainji and Shiroro dams, the study deal with the hydrological parameters such as rainfall, reservoir inflow, reservoir elevation, evaporation and turban discharge, it will cover a duration of 30 years (1987-2017). It examine and compare the spatial variations of the hydrological characteristics of the area and also use geospatial techniques to analysis the landuse pattern of the dam’s areas.

1.7   The Study Area

1.7.1 Location of the study

Geographically, Shiroro dam is located on 6° 51’ 00” E and 6° 75’ 10’’ E longitude and latitude 9° 58’ 00” N and 9° 65’ 25’’ N at 550 meters elevations downstream of the confluence of Kaduna River with river Dinya as its tributary in Shiroro Local Government Area of Niger State (Usman and Ifabiyi, 2012). Also, Kainji dam is located on Longitudes

1.7.2 Vegetation and soil of the study area

Shiroro watershed is a guinea savanna which consists of coarse grasses, shrubs and woodland (Ovie and Adeniji, 1994). The watercourse, in most areas, is characterised by evergreen short-bowled, broad-leaved trees (Ovie and Adeniji, 1994). Adegbehin et al., (2016) reported that vegetation in the areas consists of a mixture of grass, woodlands in Kainji. These are in the group of Northern Guinea savanna type. The soils in the area are sandy loam, loamy sand, and clay-loam to clay in the land bordering the river throughout the lake area. The river bedrock covered by a layer of coarse to the medium sand of variable thickness, fine sand and clay (Adegbehin et al., 2016).

The soil parent material is derived from a number of geological formations. The precambricum crystalline and metamorphosed sedimentary rocks of the basement complexes, the upper cretaceous conglomerates, sandstones and silt-stones of the Nupe formation. The alluvium varying in texture from sandy to clayed odpleistocene to recent age. The various rock types may play a decisive role in the soil derived from them and determine to a large extent their physical and chemical properties. The soil type is alluvial. Soil types within the study area are well drained shallow to moderately deep. The color varies from very dark gravity brown to dark or strong brown or yellow red the name of the soil of the Shiroro catchment area are derived from pre-existing rock i.e. Precambrian basement (complex rocks) consisting of gross, granite amphibolies schist. The soil type is also further grouped from association which are named after important features such as towns and rocks which have been used after some scientist (Raltche 1973).

1.7.3 Climate of the study area

The raining season occurred between the month April and October while the dry season came between November and March in both study area (Adegbehin et al., 2016). Kanji area has a daily maximum of 33.5oC in the warmest month while the mean annual temperature is about 30oC. The mean temperature in both seasons is 35oC (dry season) and 270C (raining season) in Shiroro area. The months of April and May are the hottest month while December and January are the coldest.  (Kuti et al, 2015).

1.7.4    Hydrology of the area

The variation in the reservoir water level is controlled by inflow into the lake (a) from the area surrounding the reservoir basin (white flood-August to November ); (b)from the upper catchment of  the Niger (black flood- December to march)(2) rainfall at the lake about 1071mm,(3) evaporation losses of the water surface estimated at 1500-2000 mm (4)seepage (5)out flood through turbines for power generating purposes (6) spilling (manly to satisfy commitments downstream) (7)domestic water use and (8)irrigation water supply (Kuti, 2015). Figure 2.1 is the hydrological map of Kainji area.

Shiroro Lake was built on river kaduna, one of the principal tributaries of river Niger, its source is from plateau mountains and travels a distance of about 356km before emptying into reservoir. Unlike the most rivers in the Northern Nigeria, river Kaduna a perennial river. The river flow in a fairly straight course in the upper and middle stage within same meaned at the lower course. Long profiles consist of a number of steep gradient valley steps which is separated by parches of others sit low gradient. Its course is interrupted where it cross hard rocks, deep gorges have been cut across the area of more pronounced steeps in the valley (Figure 1.3 Hydrological map of Shiroro). This includes the 5.0km ravine in the granite of Shiroro and the 9.5km gorge through schist of guria. Rainy season between April and October peak falls between August and September. Dry season spell usually between November and March. River Munya, SarkinPawa, Gum and Dinya are the major tributaries in the vicinity of the study area that feed the main Kaduna River (Kuti, 2015).

₦8,000.00 – DOWNLOAD FULL PROJECT DOWNLOAD FULL PROJECT Added to cart

---

---

---

---

Related Project Topics :