Influence of Land Conservation on Water Budget

INTRODUCTION

Land conservation is important and conservation of water bodies on these lands is also important as water is about 78% of the total earth surface and 97% of these is the ocean which is salty and not good for human consumption and this is the more reason why there should be proper management of the remaining percentage of water for human use. Land conservation laws in some areas also governs the water bodies available on such lands, the laws apply to both the dry land and water bodies bringing about least pollution of the general environment. Land conservation at its best depends greatly on knowing what to conserve. Understanding what land conservation and water budget means is important in determining their relationship. (1)

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Land conservation is a radical, eco-friendly and societal movement that seeks to protect natural environment including plant and animal species as well as their habitat for future use. The early conservation movement included fisheries, wildlife management, water, soil conservation, and sustainable forestry. The contemporary conservation movement has widened from the initial movement’s emphasis on use of maintainable yield of natural resources and preservation of wilderness areas to include protection of biodiversity. Some say the conservation movement is part of the larger and more extensive environmental movement, while others argue that they contrast both in philosophy and practice (2). Conservation may not always mean putting aside resources, never to be used; often, it may be a group of people working in unity to ensure sustainable resolutions for the plants, wildlife, and people who call an area home (3).  

Lately, added devotion has been shown towards Land conservation because of an increasing exposure on themes such as food security, climate change, and desertification. Further significant causes include a growing consciousness of regular land degradation and of the importance of land-related returns, which constitute the basis for agronomic production and providing of ecosystem services(4). All land conservation plans should focus on key natural resources as indicated by the biological integrity and complexity of a habitat. Land conservation should strive to be ecologically productive, socially acceptable, economically protective and risk reducing (5).

The global water budget is the projected sum of water that occurs in each area or form all over the earth. Water budget are broadly used to account for flow and storage fluctuations in several hydrologic systems, including streams, seas, drainage basins, the land surface, and ground water systems. Water budget can also be stated as Inflow – Outflow = Change in water buget.  The three  terms in the water-budget equation comprise both natural (e.g rainfall) and human-induced (e.g., imported water) components (6).

Figure 1 – a diagram showing the inflow and outflow of water .

Hydrological stability and processes in watershed are influenced by changes in land use and land cover. Those variations can impact interception, evapotranspiration (ET), infiltration, soil moisture, water balance and biogeochemical cycling of carbon, nitrogen and other elements at regional to global scales. The effects of these hydrological turbulences are generally reflected in form of cumulative runoff rate and volume, more powerful and regular floods, reducing groundwater recharge and base flow, elevated levels of residues and increase in concentration of nutrients in both streams and shallow groundwater (7). Proper land conservation laws and practices can help reduce these negative effects on the ecosystem.

LITERATURE REVIEW

Land and water degradation are closely linked, as Land degradation reduces the production of water-related ecosystem services and affects water accessibility, quality, and storage (8). As the produce of hydrological cycles on land, fresh water resources institute only 2.5% of the earth’s water. Fresh water is limited, and its global circulation was long subjugated by natural cycles of freezing and liquefying, precipitation, evapotranspiration, and runoff. The pressure on the global water system has grown due to increased human actions, such as land use, as well as altering climatic patterns (9). These developments may negatively impact surface water balance, evapotranspiration, runoff, and groundwater flow. Surface runoff and river discharge increase when natural vegetation, such as a forest is cleared (10), or when more land is cultivated. Because of this strong link between land and water productivity, improving water management in agriculture requires that land degradation be mitigated or prevented. Optimistic scenarios suggest that, by 2050, 30–40% more fresh water will be used by agriculture than is used today (11). Inadequate water quantity and poor water quality is becoming an increasing concern in the United States and other parts of the world (12). The water quantity issues are in form of increase in evapotranspiration, decrease in infiltration and soil moisture, increasing runoff rate and volume, changes in timing of spring and winter runoff event, decreasing groundwater recharge and base flow, more intense and frequent floods in some areas and droughts in the others (13). Poor water quality is another concern.

If land degradation is understood as a process that negatively affects land properties especially the water budget, it is then a process that commences almost as soon as land is tilled. Hence, human activities principally agriculture must be understood as the main driver of land degradation, even though certain land use strategies can minimize or even prevent such degradation. Like any resource, the management of land use has more to do with managing people than it does the management of land per se (14).

Human management of water and biogeochemical cycles sometimes increases productivity, accelerates internal cycling of water, energy, and nutrients, albeit often at the expense of biodiversity, resilience, and other ecosystem services (15). Thus, despite increased productivity, the very efforts to stabilize ecosystem response to small environmental fluctuations may cause over‐specialization, over‐exploitation, and hence a loss of redundancy, which in turn may increase vulnerability to extreme fluctuations (16). These systems become then unable to provide essential ecosystem services, resulting in reduced environmental quality and stability and potentially moving closer to possible tipping points and catastrophic thresholds (17).

Ineffective land conservation practices result to land degradation and ultimately having negative effects on water cycle and water productivity. The negative effects are as follows

      Loss of organic matter and the physical degradation of soil

Soil organic matter is important to managing water cycles in ecosystems. Reductions in soil organic matter favors the breakdown of soil aggregates and thus crusting and sealing of the soil surface, giving rise to reduced porosity, less infiltration, and more runoff (18). Soil surface compaction, by heavy machinery or large numbers of livestock, for example, can cause overland flow, even on usually permeable soils (19). Such changes can increase the risk of flooding and water erosion. On sloping terrain, more frequent and more intense runoff increases interrail erosion, reduces subsurface flow, and gives rise to rills and subsequently gullies. In drier environments, these processes also increase water loss through evaporation

      Soil erosion and sedimentation

Soil erosion rates almost always rise greatly with agricultural activity. Onsite, soil erosion reduces crop yields and water production by removing nutrients and organic matter. Yield impacts can be severe and vary with soil type and are particularly evident in the early stages of erosion. In Ethiopia, soil erosion reduces yields by an average of 1–2% annually, resulting in base yields of 300–500 kg/ha, while elsewhere, it has demonstrated dramatic declines on a wide range of soils. Erosion also interferes with soil–water relationships: the depth of soil is reduced, diminishing water storage capacity, and damaging soil structure thus reducing soil porosity. Surface sealing and crusting reduce infiltration and increase surface runoff, which is a problem and results in a net loss of water for crops. Downstream, the impact of soil erosion is sedimentation, a major form of human-induced water pollution (20)

      Nutrient depletion and chemical degradation of soil

Globally, only half of the nutrients that crops take from the soil are substituted. When this depletion results in essential nutrients becoming more limiting than water, water productivity declines (21). A final key chemical dilapidation problem is that of secondary salinization, which is a serious threat to sustainable irrigated agricultural production. Although data are poor, estimates indicate that, globally, 20% of wet land suffers from secondary salinization and water logging (22) induced by the build-up of salts introduced via irrigation water.

      Degradation of landscape functions

 Processes such as those above, combined with the simplification of vegetative cover, alter water cycles and have significant penalties for water quality and water accessibility. Soil degradation reduces the efficiency of natural filtration processes in landscapes, and thereby exacerbates water pollution when it increases the quantity of water that flows swiftly over land. Surface runoff carries microbes, nutrients, organic matter, pesticides, and weighty metals from surface soils to water bodies. Phosphorus levels, for example, can be approximately 10 times higher in surface runoff than in groundwater (23). There is also growing evidence that soil degradation and vegetative change that result in evaporation and convection changes can also have large impacts on local precipitation patterns and water availability (24). This is in addition to the loss of filtration functions, and base flow buffering that are considered essential regulating and supporting ecosystem services of landscapes (25). Land degradation at the landscape level has a significant impact also on biodiversity – both above and below ground – and this impairs overall ecosystem function.

      Misguided policies

Policies often artificially ratchet up the number of people per hectare of land, and/or concentrate poorer people on fragile, degradation-prone lands. Policies in Latin America often favors large landowners and provide favorable financial conditions for the expansion of large ranching areas. In Mexico, land distribution policies favors the non-poor, 80% of whom occupy more desirable flat lands, while 66% of the rural poor live on lands with a bigger than 5% slope (26). Indeed, 66% of the poor in the developing world live on marginal quality land (27)

      Population density

Poverty joined with high population densities is frequently cited as a key cause of land dilapidation (28). There can be little doubt that the rural individuals will increase in the future. The evidence, however, suggests that population mass in and of itself need not essentiallybe a cause of land degradation (29). Hence, it must be the situation within which dense populaces of land users exist that determines whether they misuse land and water.

DISCUSSION

Humans have reduced the volatility of water resources by improving land use practices, improving rate of extraction of food and fiber from ecosystem by managing vegetation, engineering landscapes, soil and drainage system and intensely controlling the quantity and quality of water. Investing in improved land management, such as with resource-conserving technologies, can considerably improve on- farm water productivity in both rainfed and irrigated agricultural systems (30). Resource-conserving agriculture covers a broad range of systems which have the potential to improve water productivity and water management in a variety of ways. For example, soil management practices to improve infiltration and soil water storage such as zero till can boost water use efficiency by an estimated 25–40%, while nutrient management can boost water use efficiency by 15–25% (31). Water productivity improvement can range from 70 to 100% in rainfed systems and from 15 to 30% in irrigated systems using resource-conserving agricultural techniques that enhance soil fertility and reduce water evaporation (32). Water productivity can be improved by implementing better adapted cropping systems, particularly in semi-arid environments (33), Examples (34) suggest that improved land management is one of the most promising ways of increasing on-farm water productivity in low- yielding rainfed systems (35).

By 2050, global food demand will be 70–90% higher than current requirements. If water productivity in agriculture remains at present levels, water demands will grow by a similar amount. At the same time, if degradation trends continue at present rates, along with an expanding area under urban development, the amount of land available to farming will decline. As such, an intensification of agriculture is the most promising option for increasing food supplies to the globe’s growing population, particularly in rainfed areas (36). To make intensification sustainable in the long term, resource degradation needs to be mitigated or prevented, while the ecosystem services of the land need to be increased (37). A focus on smallholder agricultural systems to achieve the required intensification not only of land, but also water use and improved water management, makes sense because of the great extent of these farming systems and their resource efficiency. The smallholder unit is an important intervention point for influencing land and water use management to have a discernable, positive impact onrural livelihoods because the largest proportion of the developingworld’s undernourished people are concentrated among smallholder agricultural groups (38).

CONCLUSION

Land-use changes as seen in this paper undeniably affects the water budget through changes in evapotranspiration, runoff, and ground-water recharge. Various activities by man which includes irrigation of lawns, gardens, and parks, which, in turn, increase water available at the land surface for increased evapotranspiration. Runoff increases and re- charge in wet areas may be reduced, whereas recharge in dry areas may increase because of irrigation. Higher density urbanization enhances runoff, decreases evapotranspiration, and may increase recharge. Irrigated agriculture, however, has the greatest effect on the water budget. With land so intimately linked with the water budget, how we treat our land really influences the availability of safe water for human use, it is therefore necessary to enforce proper land use for better ecosystem services.

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