Groundwater Condition and Management in Kano Region , Northwestern Nigeria

This paper provides a broad overview of issues on groundwater condition and management in the Kano region of northwestern Nigeria. The aim is to recommend new management strategies that can ensure sustainable groundwater resource management in the region. To achieve the aim of the study, various studies on groundwater conducted in the region were reviewed and key issues were identified. The review revealed that groundwater availability varied between the Basement Complex and Chad Formation areas of the region, with the latter having more of the resource than the former region as a result of the migration of groundwater from the Basement complex to the Chad Formation region. The review also revealed a steady annual decrease of groundwater level during the period 2010 to 2013 and the groundwater beneath the floodplains dropped from 9000 Million Cubic Meter (MCM) in 1964 to 5000 MCM in 1987 in the Chad Formation area of the region. The review further revealed that there is poor knowledge regarding the impact of historical and projected climate variability and change on groundwater availability in the region. This is as a result of the lack of sustained time series data on groundwater resource. Thus, there has been little or no integrated management between groundwater excess and deficiency on one hand, and groundwater pollution management on the other hand. Rainwater harvesting, among other approaches, is recommended for sustainable groundwater management in the region.


Introduction
The importance of water to life on earth, particularly to human beings, becomes clearer when one considers its role or usefulness in various aspects of human endeavor [1].As such water is at the centre of Sustainable Development Goals (SDGs) numbers 1, 3, 6 and 16 [2].In many parts of the arid and semi arid regions, reliance on groundwater has increased significantly mainly due to inadequate rainfall and the consequent surface water scarcity [3].Many people in developing countries particularly in Sub-Saharan regions generally rely on groundwater sources for potable water [4].In many African countries such as Niger, Botswana, and Ghana, groundwater accounts for 71.43%, 50% and 47.56%, respectively, of their total freshwater sources [5] and accounts for over 60.9% of the domestic supply in the Ejisu-Juaben municipality of the Ashanti Region of Ghana [6].Similarly, groundwater is the main source of water to about 70% of the inhabitants of Meru City, Tanzania [7].Although groundwater accounts for only 28.90% of the total freshwater in Nigeria [5], about 128 million people (85% of the total population) depended on this resource as at 2001 mainly due to the deterioration in the quality and quantity of surface water, insufficient water supply by water authorities, effect of climate change and above all rapid population growth [8].In the northern part of Kano region, the interplay of hydrologic and geological characteristics makes surface water virtually inadequate, and as such groundwater appears to be the only reliable source of fresh water for domestic and agricultural use [9].
Although water is necessary for human survival, many urban areas of the world have been experiencing water shortages, which are expected to explode in this century unless serious measures are taken to reduce the scale of this problem [10].In sub-Saharan Africa, at least 44% of the populations (about 320 million people) do not have access to clean reliable water supplies [11].In the dry land regions, such as northwestern Nigeria, this problem of groundwater deterioration can be worsened by prolonged drought as a result of climate change and desertification process, and it is predicted that these regions will be under the threat of groundwater quantity and quality challenge in the near future [12].
Kano region in northwestern Nigeria is currently home to nearly 34% of the nation's population.The region covers seasonally humid and semi-arid regions accounting for 65% of the total population of northwestern regions [13].However, natural and anthropogenic influences such as drought, desertification, rapid population growth, agricultural development coupled with pollution from industrial activities and domestic sewage have been identified as effective factors leading to imbalance between water supply and demand as well as the general quality of both surface and groundwater resources in the region [13].It is worth mentioning that the region has not yet acknowledged the extent of the problems of water availability in the area.This is evidenced by the absence of any long-term strategies for water management.As such, balancing water availability and rising population (human demand) is the major challenge in the region.
Groundwater resource management has been identified as the contentious issue, principally in the dry land regions where rapid population growth and rainfall variability make the availability of surface water inadequate and the inadequacy adds more pressure to the existing groundwater resources.It is for this reason that this paper provides a broad overview of groundwater condition and management in the Kano region of northwestern Nigeria with a view of providing key issues regarding groundwater resources management that needs to be addressed.Specifically, the paper aims at (i) Identifying areas with groundwater deficiency and challenges in the region; (ii) Determining groundwater quality status in the region; (iii) Recommending what should be the focus of groundwater management in the region.
It is hoped that the review will go some way towards assisting policy makers, institutions, and other stakeholders in addressing what remains the greatest challenge regarding groundwater management issues in the region.

Geographical Background of Kano Region
Kano region, according to [14], has been defined as the political States of Kano and Jigawa which previously constituted a single state.Kano regionis located in the dry land zone of Nigerian northwest (Figure 1).It is the most populous region in the whole of Nigeria and it is characterized by rainfall variability around a long-term annual total ranging from less than 600 mm in the northernmost parts to 800 mm in the middle (around Kano City) to 1000 mm in the southern tips.The duration of the wet season in that order ranges from 4 months in the northernmost through 5 months in the middle to 6 months in the southern tips during most of the years.The remaining months of the year are dry.The region extends over two major geological structures separated by an interface known as the hydrological divide (Figure 2).The southern and western parts of the Divide are underlain by the Basement Complex rocks and the northeastern parts by the sedimentary ChadFormation (Figure 2).The Basement Complex rocks consist mostly of igneous and metamorphic rocks with relatively shallow weathered mantle that permits very limited groundwater content.On the other hand, the Chad Sedimentary Formation consists largely of unconsolidated porous sandy sediments in which aquifers exist in three known layers, two top ones of which are accessible to borehole exploitation.Besides, there are alluvial deposits on river floodplains easily exploited for the groundwater through tube wells.Thus, the two major structures of the region have influenced the available groundwater quantity and variation in the region.That is, groundwater availability varied between the southern and northeastern region, with the latter having abundance of groundwater resource and the former with more of surface water resource [15].In all the locations, the existing water resource management strategy is virtually inadequate; as such pressure is mounted on the available groundwater for various uses, principally in the northeastern part of the region.Figures 3 and 4 show the land use and elevation of the region, respectively.an interface known as the hydrological divide (Figure 2).The southern and western parts of the Divide are underlain by the Basement Complex rocks and the northeastern parts by the sedimentary ChadFormation (Figure 2).The Basement Complex rocks consist mostly of igneous and metamorphic rocks with relatively shallow weathered mantle that permits very limited groundwater content.On the other hand, the Chad Sedimentary Formation consists largely of unconsolidated porous sandy sediments in which aquifers exist in three known layers, two top ones of which are accessible to borehole exploitation.Besides, there are alluvial deposits on river floodplains easily exploited for the groundwater through tube wells.Thus, the two major structures of the region have influenced the available groundwater quantity and variation in the region.That is, groundwater availability varied between the southern and northeastern region, with the latter having abundance of groundwater resource and the former with more of surface water resource [15].In all the locations, the existing water resource management strategy is virtually inadequate; as such pressure is mounted on the available groundwater for various uses, principally in the northeastern part of the region.Figures 3  and 4 show the land use and elevation of the region, respectively.an interface known as the hydrological divide (Figure 2).The southern and western parts of the Divide are underlain by the Basement Complex rocks and the northeastern parts by the sedimentary ChadFormation (Figure 2).The Basement Complex rocks consist mostly of igneous and metamorphic rocks with relatively shallow weathered mantle that permits very limited groundwater content.On the other hand, the Chad Sedimentary Formation consists largely of unconsolidated porous sandy sediments in which aquifers exist in three known layers, two top ones of which are accessible to borehole exploitation.Besides, there are alluvial deposits on river floodplains easily exploited for the groundwater through tube wells.Thus, the two major structures of the region have influenced the available groundwater quantity and variation in the region.That is, groundwater availability varied between the southern and northeastern region, with the latter having abundance of groundwater resource and the former with more of surface water resource [15].In all the locations, the existing water resource management strategy is virtually inadequate; as such pressure is mounted on the available groundwater for various uses, principally in the northeastern part of the region.Figures 3  and 4 show the land use and elevation of the region, respectively.

Methods
A bibliographic survey based on Google Scholar Citation Index and the Science Citation Index Expanded (SCIE) database was conducted to evaluate groundwater-related research in the area covering different perspectives (Table 1).Further, a survey of groundwater yield and quality in the floodplain along the basin was conducted covering a transect of about 135 km during two distinctive seasons of one year (dry and rainy) to ascertain the findings of previous studies concerning the

Methods
A bibliographic survey based on Google Scholar Citation Index and the Science Citation Index Expanded (SCIE) database was conducted to evaluate groundwater-related research in the area covering different perspectives (Table 1).Further, a survey of groundwater yield and quality in the floodplain along the basin was conducted covering a transect of about 135 km during two distinctive seasons of one year (dry and rainy) to ascertain the findings of previous studies concerning the groundwater condition in the region.Six transects were established within one km 2 of each selected point along the basin and were oriented perpendicular to the river channel.Three tube wells were sampled and positioned along each transect at regular intervals making a total of 18 wells.A pumping test, which was repeated four times at 15 min interval in both morning and evening hours was used to measure groundwater yield.The sampling standard methods prescribed by American Public Health Association [16] were followed carefully for the groundwater samples collection to determine the concentration of water quality indices presented in Table 2. Eleven water quality indices representing four hazard classes (Salinity hazard, Permeability/infiltration hazard, Specific ion toxicity hazard and Miscellaneous hazard) were used.They include Electrical Conductivity (EC), Sodium Absorption Ratio (SAR), Percent Sodium (%Na), Kelly's Ratio (KR), Magnesium Hazard (MH), Permeability Index (PI), Boron (B), Chloride (Cl − ), Residual Sodium Carbonate (RSC), pH and Bicarbonate (HCO 3 − ).
Six of the indices were computed using the equations below: %Na = ( A weighted arithmetic method was used in computing the Irrigation Water Quality Index (IWQI).Multivariate statistical tools such as analysis of variance, Pearson product moment correlation, and Cluster Analysis (CA) were used respectively, to test the research hypothesis and to classify sampling points into similar groups based on groundwater yield and dynamic level.To assess the suitability of groundwater for drinking in the Basement Complex area of Kano, Nigeria.
Twenty sample of groundwater were collected from boreholes randomly located in five different geological settings (quartzite, granite, gneiss and schist) of the area.Simple descriptive statistics were used to present the result.
The quality of the sampled water were found to be within the WHO acceptable limit for drinking.Rock-water interaction & weathering play a vital role in the concentration of the investigated parameters.
No rigorous statistical tools used in analyzing the data.9 Umar, (2016) [24] To identify groundwater level fluctuation in Kano Sedimentary formation area, Northwester Nigeria Groundwater level data of 4 years were obtained from the Hadejia River Basin Development Authority, Kano office.Simple descriptive statistics were used in analyzing the data.
There is steady decline of groundwater level from 2010 to 2013.
Over-abstraction of groundwater coupled with inadequate rainfall were identified as the key factors for that.To assess the effect of rainfall factor on groundwater recharge in Banghar Environs, India Statistical analysis such as mean, median, mode and the co-efficient standard deviation, co-efficient of dispersion, co-efficient of variation and co-efficient of skewness were used to analyze the data.
The years revealing more than the average annual rainfall values indicate positive recharge of groundwater trend and vice versa.Cumulative departure exhibit positive and negative trends and the determination of moving rainfall average provide a picture of cycle variation of rainfall trend.
It is suggests that implementation of a rainfall augmentation scheme would provide appropriate rainfall recharge to the groundwater system and it would also resolve the water crises problem Reactive modeling is thought to be an efficient and robust tool to quantify the complex biogeochemicalreactions which can take place in undergroundenvironments 13 Colombani, et al.
(2016) [28] To quantify the present and potential (2050) salinization of a coastal aquifer in the Po Delta, Italy A combination of SEAWAT 4.0 and PESTwas used for the prediction and automatic inverse parameter calibration, respectively.
Results show that the Po Delta will experience a significant salinization by 2050 and that the major cause is autonomous salinization via seepage of saline groundwater rather than enhanced seawater intrusion due to sea level rise.
This scenario allowed us to identify the zones that are more affected by the relative sea level rise and to quantify the increase in salinization of groundwater.To present the first quantitative maps of aquifer storage and potential borehole yields in Africa The study made extensive review of available maps, publications and data on groundwater availability and yield in Africa.
Groundwater storage was estimated to be 0.66 million km 3  The study could have used geospatial tool to map the distribution of groundwater quality indices in the study area.

Concept of Water Resources Management
The principal need for water resources management is primarily due to the fact that the hydrological cycle does not adapt itself to man's requirements for water over space or time.Consequently, water is usually not available in the quantity and quality required and at the time it is needed.Thus, strategies are put in place to develop and manage water in a manner that will make it available in the quantity and quality required and in the place and time it is needed [44].The objective of water resource management in any region therefore is to achieve satisfaction between water availability and demand in both space and time through the modification of the hydrological cycle [45].This involves not only the beneficial use of water resources, but also the prevention, avoidance or minimization of the effects of either water deficiency (drought), water excess (flood), water pollution or both.

Groundwater Availability and Uses
Groundwater availability varied in the region.Various factors affect its availability.The most recognized and important one is the geological differences.In his study [16], revealed that, the volume of groundwater decreases from the Chad Formation to the Basement Complex region, with Birniwa area in the former region and Zarewa in the later region having a respective volume of 9, 363.0 m 3 and 49.0 m 3 of groundwater.Thus, groundwater availability is much higher in the Chad Formation than in the Basement Complex.The Chad Formation in the Kano region is one of the largest accessible stores of fresh groundwater, and for that groundwater is often considered a logical resource in the region.Conversely, in the Basement Complex region, rapid rising population growth in association with urbanization and change in climate have led to intensive exploitation of groundwater through construction of boreholes, principally for domestic water supply.Groundwater in the urban Kano area for instance appears to be a common and low-cost alternative to surface water for many uses because it occurs generally in a more potable quality compared to surface water.However, despite the growing dependency upon groundwater for different uses in urban Kano, concerns remain over the sustainability of this resource principally in terms not only of the rate of abstraction but also in terms of the quality and quantity because the area is underlain by igneous structure.
The uses of groundwater in the region varied from commercial, domestic and agricultural uses.In the northeastern part of the region, groundwater is the only source of fresh water for various domestic uses.Similarly, the resource appeared to be the only alternative and reliable source of water for various agricultural activities, especially, the floodplain (fadama) irrigation agriculture.While rain-fed agriculture lasts for about three to four months in the area, floodplain irrigation is well practiced throughout the dry season lasting for six to nine months.Thus, groundwater from fadama aquifer is extracted by tube wells and wash bores to support irrigation in the dry season from the end of the rainy season, which provides opportunities in terms of agricultural diversification than in the southern region and enables for double or triple cultivation in one single year.In the southern part of the region, however, groundwater becomes virtually the most reliable source of fresh water for domestic and commercial activities.Increase in the level of demand and consumption of water leads to the drilling of boreholes by individuals, government and private companies.Consequently, thousands of commercial water companies have emerged increasingly particularly in the urban areas of the region to exploit principally groundwater as the main source of potable water.The reliance of groundwater this way is a result of the inefficiency of the personnel of Water Works who are responsible for treating surface water for distribution to users, more so since the pipes and taps for such distribution are virtually permanently dry and the ponds, lakes and rivers are highly polluted.In addition, existing and newly constructed houses in the residential locations also rely on this resource as the reliable source of freshwater for their domestic use.

Groundwater Depletion
The findings of [46], on groundwater availability in the region, revealed that the mean groundwater recharge contributed by river flow and rainfall accounted for 33% and 13%, respectively.The study further revealed, according to [19], that groundwater beneath the floodplains dropped from 9000 MCM in 1964 to 5000 MCM in 1987 (a drop of about one half of its initial value).In the same development, the finding of [47] on the variation of groundwater level in the same northern region of Kano revealed a positive relationship between rainfall and groundwater level variation.Thus, the study revealed a steady annual decrease of groundwater level from 2010 to 2013 in the area (Figure 5).

Groundwater Depletion
The findings of [46], on groundwater availability in the region, revealed that the mean groundwater recharge contributed by river flow and rainfall accounted for 33% and 13%, respectively.The study further revealed, according to [19], that groundwater beneath the floodplains dropped from 9000 MCM in 1964 to 5000 MCM in 1987 (a drop of about one half of its initial value).In the same development, the finding of [47] on the variation of groundwater level in the same northern region of Kano revealed a positive relationship between rainfall and groundwater level variation.Thus, the study revealed a steady annual decrease of groundwater level from 2010 to 2013 in the area (Figure 5).Similarly, the finding of [16] projected groundwater deficiency in the southern Kano region as the resource was found to be migrating to the north eastern part of the region.In addition to this, rapid rising population growth coupled with the poor knowledge regarding the relationship between current climate variability and groundwater availability all can lead to groundwater deficiency in the region.
In the same development, the finding of [25] revealed that, groundwater average yield in the fadama land of the region was found to be within the standard (2.5 L/s) for irrigation (Table 3).Although, yield in some locations, particularly, in Miga and Auyo haveminimum average yields of 0.5 and 1.3 L/s, respectively, which are considered unsuitable for irrigation.Overexploitation of the aquifer due to intensive irrigation activities can be a reason for this lowest yield, as Auyo and Miga are among the leading fadama irrigation towns, after Hadejia.Moreover these locations coincided with the towns where tube wells were built by the Macdonald and Diyam Consulting Company in 1962 over three decades now.Average yield of wells for evening hours recorded higher yield (56%) than the yield in morning hours (44%), in the region with the result of 2-way ANOVA showing significant diurnal variation (p value 0.00 < 0.05) in the yield of wells.Furthermore, correlation test showed significant relationship between groundwater dynamic level and yield among the study locations (p value, 0.045 < 0.05).Similarly, the finding of [16] projected groundwater deficiency in the southern Kano region as the resource was found to be migrating to the north eastern part of the region.In addition to this, rapid rising population growth coupled with the poor knowledge regarding the relationship between current climate variability and groundwater availability all can lead to groundwater deficiency in the region.
In the same development, the finding of [25] revealed that, groundwater average yield in the fadama land of the region was found to be within the standard (2.5 L/s) for irrigation (Table 3).Although, yield in some locations, particularly, in Miga and Auyo haveminimum average yields of 0.5 and 1.3 L/s, respectively, which are considered unsuitable for irrigation.Overexploitation of the aquifer due to intensive irrigation activities can be a reason for this lowest yield, as Auyo and Miga are among the leading fadama irrigation towns, after Hadejia.Moreover these locations coincided with the towns where tube wells were built by the Macdonald and Diyam Consulting Company in 1962 over three decades now.Average yield of wells for evening hours recorded higher yield (56%) than the yield in morning hours (44%), in the region with the result of 2-way ANOVA showing significant diurnal variation (p value 0.00 < 0.05) in the yield of wells.Furthermore, correlation test showed significant relationship between groundwater dynamic level and yield among the study locations (p value, 0.045 < 0.05).

Groundwater QualityStatus
The findings of [25] revealed that, groundwater suitability declines in the dry season than in the rainy season based on the four groundwater hazard classes (salinity, permeability/infiltration, specific ions toxicity and miscellaneous hazards) investigated.This is because irrigation is more intensive in the dry season with over exploitation of groundwater and intensive application of fertilizer in the soil due to the delay of on-set and short duration of rainfall period in the area.The order of dominance of groundwater quality class based on the result of Irrigation Water Quality Index (IWQI) model is: moderate > good > doubtful > excellent (Figure 6).This suggests that, groundwater along the basin can be used for irrigation without much problem to soil, since the soils of the study locations have excellent to good permeability condition as shown by the results of indices of permeability/infiltration hazards (SAR, %Na, KR, PI, MH).Similarly, vegetable crops can grow well as they have moderate tolerance to salt based on salinity hazard.However, overexploitation and intensive application of fertilizers can induce water quality deterioration.This problem can be worsened when the present permeability condition (good) of the soil also possess deterioration.

Groundwater QualityStatus
The findings of [25] revealed that, groundwater suitability declines in the dry season than in the rainy season based on the four groundwater hazard classes (salinity, permeability/infiltration, specific ions toxicity and miscellaneous hazards) investigated.This is because irrigation is more intensive in the dry season with over exploitation of groundwater and intensive application of fertilizer in the soil due to the delay of on-set and short duration of rainfall period in the area.The order of dominance of groundwater quality class based on the result of Irrigation Water Quality Index (IWQI) model is: moderate > good > doubtful > excellent (Figure 6).This suggests that, groundwater along the basin can be used for irrigation without much problem to soil, since the soils of the study locations have excellent to good permeability condition as shown by the results of indices of permeability/infiltration hazards (SAR, %Na, KR, PI, MH).Similarly, vegetable crops can grow well as they have moderate tolerance to salt based on salinity hazard.However, overexploitation and intensive application of fertilizers can induce water quality deterioration.This problem can be worsened when the present permeability condition (good) of the soil also possess deterioration.

3.5.Recommended Management Strategies
In view of the threat associated with the anticipated groundwater deficiency in the region and the apparent ineffective existing management options, the following management strategies are hereby proposed to enhance the conservation of the available groundwater resource for sustainable use.

Managed Aquifer Recharge
Manage Aquifer Recharge (MAR) is considered as one of the sustainable methods to manage groundwater resource especially in the dry land regions through artificial aquifer recharge (AAR).AAR has many advantages over conventional surface water storage such as dam construction especially in the basement complex area of Kano region.These advantages include negligible evaporation losses, limited vulnerability to secondary contamination by animals and or human and no algae blooms resulting in decreasing surface water quality.The flow of water through the subsurface provides soil-aquifer treatment (SAT), along with aquifers providing seasonal and/or longer storage.

Recommended Management Strategies
In view of the threat associated with the anticipated groundwater deficiency in the region and the apparent ineffective existing management options, the following management strategies are hereby proposed to enhance the conservation of the available groundwater resource for sustainable use.

Managed Aquifer Recharge
Manage Aquifer Recharge (MAR) is considered as one of the sustainable methods to manage groundwater resource especially in the dry land regions through artificial aquifer recharge (AAR).AAR has many advantages over conventional surface water storage such as dam construction especially in the basement complex area of Kano region.These advantages include negligible evaporation losses, limited vulnerability to secondary contamination by animals and or human and no algae blooms resulting in decreasing surface water quality.The flow of water through the subsurface provides soil-aquifer treatment (SAT), along with aquifers providing seasonal and/or longer storage.

Reclamation and Re-Use
Water reclamation and re-use have become an attractive options for conserving and extending available groundwater resources especially in the dry land of the world, as urban areas in these regions approach and reach the limit of their available groundwater supplies.Reclamation and re-use techniques of wastewater can be adopted as an alternative to over-reliance on groundwater management especially in the southern Kano region where wastewater from municipal areas is common everywhere.This can be achieved through recharging groundwater with the reclaimed or recycled municipal wastewater.The purpose is to reduce, stop or even reverse declines of groundwater level.The treated water percolates through the soil mantle and unconfined aquifer, mix with native groundwater and eventually recovered and use again.

Rainfall Harvesting
Rainfall harvesting has been used as a supplementary or even primary water source for different uses especially in the semi-arid regions of the world where rainfall is sufficient only for short-season crops production.Rainwater harvesting provides a significant amount of freshwater in countries with insufficient rainfall [20].Examples include: Kuwait (12% of the water demand for landscape agriculture); Muscat, Oman (27% of the water demand for industry); Abha, Saudi Arabia (11% of water demand for industry and landscape irrigation); and Ali Ain, United Arab Emirates (16% of water demand for agriculture).In view of the successes made in other countries, the same management practice can be put in use in Kano region, especially in the Chad Formation area where geology and rainfall characteristics make surface water virtually unavailable.This can serve as an alternative source of surface water resource at household or small community level.

Management of Wet Season Groundwater Excess
Kano region is one of the dry land regions of Nigeria with known flood hazards.The region recorded 17% of the total floods experienced in Nigeria during 2012 [48].Excess groundwater in the region occurs during the rainy season of the year when rainfall is heavy and the amount is sufficient to recharge the aquifers through soil infiltration of direct rainwater and seepage from rivers and their tributaries, especially in the Chad Formation region with high infiltration capacity.In this period, groundwater level rises to a higher level in the aquifer thereby increasing the quantity.This rising groundwater level is evident in most of the domestic wells both in urban and village areas of the region as well as in shallow tube wells of the floodplain.This wet season excess groundwater in the region often aids flooding, especially in the floodplains of Chad Formation region, leading to crop destruction that adversely impacts on farmers' livelihood.In view of the challenge of floodplain flooding resulting from excess groundwater and heavy rainfall, floodplain management is hereby recommended for managing wet season excess groundwater in the region.

Floodplain Management
Floodplain management is the operation of an overall programme of corrective and preventive measures for reducing flood damage, including, but not limited to, emergency preparedness plans; flood control works and floodplain management regulations.Floodplain management regulations were recognized as the most effective method for preventing future flood damage, especially in developing countries with known flood hazards [20].Flood control measures both structural (flood control facilities) and nonstructural are used to regulate the flood runoff.Structural measures include reservoirs, diversions, levees or dikes and channel modifications, while nonstructural measures include flood proofing, flood early warning system and land use control.

Discussion
Groundwater resources in Kano region were found to be migrating from southwest to the north eastern part of the region.A drop of about one half of shallow groundwater initial value was observed between 1964 and 1987.Evening hours recorded higher yield than morning hours.CA was also applied to the dynamic level data of groundwater across the sampling sites.The result is presented as a dendrogram in Figure 7, grouping all the five sampling sites into three statistically significant clusters: Cluster 1 (Guri), cluster 2 (Ringim), cluster 3 (Miga, Hadejia and Auyo).Guri and Ringim appeared to be in separate and independent clusters, meaning that, their groundwater dynamic level is significantly different.The reason that can be attributed to the fact that the groundwater dynamic level of Guri and Ringim is significantly differently from the others is because they are at the two extremes locations of the study area along the basin.In other words, Ringim is the first sampling site in the south western part of the basin in Kano State, while Guri is the last sampling site located in the extreme end (north east) of Jigawa State in the Chad Formation near Yobe State.The last cluster comprising of Miga, Hadejia and Auyo suggests that their groundwater dynamic levels are somewhat similar.Data collected from field work revealed that groundwater dynamic level increases with distance toward northeast along the basin.The result of CA supported the data collected.The fact that the CA result supports the collected data suggests that relying on sampling fewer CA sites for monitoring groundwater dynamic levels will not affect adversely the data gathered individually from more sampling sites.That is, one sample from the Hadejia-Miga-Auyo cluster and one each from the other two clusters would have yielded the same results as realized in this study from five sites.One of the implications is that groundwater decline will worsen the situation in the basement complex region which houses large proportion of the region's population.Consequently, groundwater deficiency is apparent in the southwestern part of the region which lies on igneous structure and access to water constitutes a great challenge because of the large population.Also, because the study area is among the dry (semi-arid) regions in Nigeria, which is characterized by prolonged dry season with high demand on groundwater for irrigation due to inadequate surface water availability, routine monitoring of groundwater availability and quality is very important.Such monitoring, principally the salinity condition has been recommended over three decades ago by the Macdonal and Diyam Consulting Company (Kano City, Kano State, Nigeria).
Hydrology 2018, 5, x 13 of 22 also applied to the dynamic level data of groundwater across the sampling sites.The result is presented as a dendrogram in Figure 7, grouping all the five sampling sites into three statistically significant clusters: Cluster 1 (Guri), cluster 2 (Ringim), cluster 3 (Miga, Hadejia and Auyo).Guri and Ringim appeared to be in separate and independent clusters, meaning that, their groundwater dynamic level is significantly different.The reason that can be attributed to the fact that the groundwater dynamic level of Guri and Ringim is significantly differently from the others is because they are at the two extremes locations of the study area along the basin.In other words, Ringim is the first sampling site in the south western part of the basin in Kano State, while Guri is the last sampling site located in the extreme end (north east) of Jigawa State in the Chad Formation near Yobe State.The last cluster comprising of Miga, Hadejia and Auyo suggests that their groundwater dynamic levels are somewhat similar.Data collected from field work revealed that groundwater dynamic level increases with distance toward northeast along the basin.The result of CA supported the data collected.The fact that the CA result supports the collected data suggests that relying on sampling fewer CA sites for monitoring groundwater dynamic levels will not affect adversely the data gathered individually from more sampling sites.That is, one sample from the Hadejia-Miga-Auyo cluster and one each from the other two clusters would have yielded the same results as realized in this study from five sites.One of the implications is that groundwater decline will worsen the situation in the basement complex region which houses large proportion of the region's population.Consequently, groundwater deficiency is apparent in the southwestern part of the region which lies on igneous structure and access to water constitutes a great challenge because of the large population.Also, because the study area is among the dry (semi-arid) regions in Nigeria, which is characterized by prolonged dry season with high demand on groundwater for irrigation due to inadequate surface water availability, routine monitoring of groundwater availability and quality is very important.Such monitoring, principally the salinity condition has been recommended over three decades ago by the Macdonal and Diyam Consulting Company (Kano City, Kano State, Nigeria).In view of the above findings and in addition to the recommended management strategies given for groundwater excess, deficiency and pollution minimization, this paper further recommends that government, donor agencies and other stake holders of the region should invest in scientific researches on groundwater in order to understand and come up with a reliable estimate of In view of the above findings and in addition to the recommended management strategies given for groundwater excess, deficiency and pollution minimization, this paper further recommends that government, donor agencies and other stake holders of the region should invest in scientific researches on groundwater in order to understand and come up with a reliable estimate of the available groundwater resource as well as to document up-to date time series data that can help in bridging the current existing gap in knowledge regarding the impact of climate variability and change on groundwater resource.

Conclusions
This paper reviews issues on groundwater management in Kano region and analyzed groundwater samples from selected fadama sites.The study revealed that groundwater resource availability varied between the Basement Complex and Chad Formation areas of the region, with the latter having more of the resource than the formerregion as a result of the migration of groundwater from the Basement complex to the Chad formation region as found by [16].The study concludes that monitoring of groundwater dynamic levels is very important to sustainable floodplain irrigation.One other conclusion that arises from the study is that instead of gathering data for the exercise from many individual sites, the sites can be grouped into clusters of similar characteristics and a single sample from an appropriate site in a cluster will appropriately represent all the floodplain sites in the cluster.However, the review of existing practices revealed that there is poor knowledge regarding the impact of historical and projected climate variability and change on groundwater availability in the region as a result of the lack of sustained time series data on groundwater resource.Also, there has been little or no integrated management of water resources between times of groundwater excess and times of deficiency on one hand, and groundwater pollution management on the other hand.This study recommends, therefore that groundwater dynamic level monitoring should be undertaken regularly in order to generate time series data that can be used to undertake integrated groundwater management in the region.It is hoped that if these recommendations are adopted, the sustainability of groundwater resource can be achieved in Kano region.

Figure 2 .
Figure 2. The Geology of Kano Region.

Figure 2 .
Figure 2. The Geology of Kano Region.

Figure 2 .
Figure 2. The Geology of Kano Region.

Figure 3 .
Figure 3. Land Use Map of Kano Region.

Figure 4 .
Figure 4. Elevation and Drainage of Kano Region.

Figure 4 .
Figure 4. Elevation and Drainage of Kano Region.

Figure 4 .
Figure 4. Elevation and Drainage of Kano Region.
Chloride-sulphate & bicarbonate were found to be the dominant water facie, indicating dissolution and/or weathering of minerals along the flow paths Geospatialt & geochemical techniques would have been better in presenting the result.

Figure 5 .
Figure 5. Annual trend of rainfall and groundwater level in the Hadejia.

Figure 5 .
Figure 5. Annual trend of rainfall and groundwater level in the Hadejia.

Figure 6 .
Figure 6.Suitability of fadama groundwater quality based on IWQI model along Hadejia River Basin.

Figure 6 .
Figure 6.Suitability of fadama groundwater quality based on IWQI model along Hadejia River Basin.

Figure 7 .
Figure 7. Dendrogram showing the cluster of sampling sites based on the groundwater dynamic levels along the basin.

Figure 7 .
Figure 7. Dendrogram showing the cluster of sampling sites based on the groundwater dynamic levels along the basin.

Table 1 .
Summary of Reviewed Groundwater-related Studies in Kano Region.

Table 2 .
Irrigation water standards, weight coefficient and relative weight of the hydrochemical parameters for IWQI.

Table 3 .
Diurnal variation of groundwater yield along Hadejia River Basin.