Irregularities in Rainfall and Its Role in Aggravating land Degradation

INTRODUCTION

Desertification is the biggest environmental challenge where the Arid, semi-arid and dry sub-humid land is affected primarily. Lessor fluctuating rainfall creates water scarcity in the dry areas and makes the land susceptible to the degrading condition called ‗Desertification‘. This problem is not only limited to the people living in deserts and surrounding areas but the problem is amplifying beyond that. Desert fringes are most likely to suffer. Multiple factors drive the forces to degrade the land but human activities and climatic changes are the most prominent. Global warming is a major cause behind the climatic changes, which contribute to desertification and leads to poor management of land. Breaking down of rocks and removal of blocks due to variation in temperature, erosion of fertile topsoil due to excess rainfall or human activities such as agriculture (ploughing, excess watering), deforestation, over-grazing etc. has been exacerbating the process. Around 29.32% area of total geographical land in India is under desertification (during 2011-2013). Approximately 96.40 mha area of the country is undergoing land degradation. Jharkhand, Rajasthan, Delhi, Gujarat and Goa states have more than 50% of the area under desertification concerning the total geographical area of the country. Rajasthan is the largest state of India (area wise) with the highest area affected by high desertification. The most important process of land degradation in the state is wind erosion (44.41%), next comes vegetation degradation (7.62%) followed by water erosion (6.18%). The most significant process of desertification/ land degradation in the country is Water Erosion (10.98% in 2011-13 and 10.83% in 2003-05) which is caused mainly due to excess rainfall in few seasons and scarcity in others. Analysis of rainfall data of Ajmer district in Rajasthan shows clear fluctuations in monsoon. Rainfall plays an important role in the assessment of land degeneration. Variations between annual rainfall patterns pose a threat of aggravating dryland degradation. Less rainfall can be the cause of drought and rising temperature along with it can cause prolonged dryness. Excessive rainfall, on the other hand, is more dangerous as it causes surface run-off and soil erosion. Rainfall meets land at the soil surface. Desertification is a condition which exacerbates runoff and soil evaporation and decreases infiltration, the water-retaining capacity of soil and transpiration.

consequences- Roy.L.Behnke (2017)-Different authors possess different views on desertification. The opening chapters of the book talk about the late twentieth-century desertification crisis in the Sahel. The author considers it as a non-event and states that the droughts did not happen due to over-exploitation by the local people rather it was the result of global climatic changes brought about by changes in the composition of atmospheric greenhouse gases and particulates. State of India’s environment (2017): A Down To Earth Annul- According to the studies, nearly 30% of India is facing desertification. Of India‘s total geographical area 328.72 million hectares, 96.40 mha is under desertification. 26 out of 29 Indian states have reported an increase in the area undergoing desertification in the past 10 years. Major reasons include- · Water erosion- responsible for 10.98 % desertification · Vegetation degradation- contributes to 8.91% desertification · Water erosion- 5.55% desertification is because of this factor · Salinity- 1.12% desertification is due to this factor. · Human made settlement- responsible for 0.69% desertification. · Others- other factors contribute to 2.07% desertification.

Along with climatic variations, human activities are equally responsible for the process of desertification. Arid, Semi-arid and dry sub-humid regions are prone to land degradation. Two important questions have been answered in this work-(i) the rates of processes that translocate the sediments/solutes and, hence, degrade a particular land, and (ii) the impact of such translocations on productive capacities of the land.

OBJECTIVES

The objectives of this research paper are to know the role of fluctuations of rainfall in Ajmer district of Rajasthan and its impact on land degradation. We can also forecast the amount of rainfall in the coming

COLLECTION

The data used for the analyses is secondary data collected from the secretariat, Ajmer district. The data is an accumulation of annual rainfall collected every year at 20 stations of Ajmer district. Cumulative data for the last 20 years (1999-2019) has been taken for the trend analysis by curve fitting method for a straight line. Principle of least squares is used for straight-line curve fitting. The straight-line trend between the given time series value is given by y= a+bt.

Table showing the calculation of Trend values for the data.

there is a straight line trend which shows that there is an overall tendency of growth in Rainfall. The peaks in the graph, crest and trough show the excess and least rainfall in particular years. There is no cyclic component in the data and few seasonal changes are due to the geographical factors such as El-Nino and La- Nina. Based on the results we can state that although there is a general trend of increase in rainfall data there are ample fluctuations which may be arising due to many reasons. These fluctuations are responsible for aggravating land degradation. We can also forecast rainfall.

SOLUTIONS

The major problem with excess rainfall is of runoff. It causes soil erosion and makes land unproductive. The water-retaining capacity of the soil is reduced. The groundwater table is not recharged and the problem intensifies. We need to stop deforestation and overgrazing by animals to protect fertile soil from getting washed away. Prevention is a lot more cost-effective than rehabilitation. The best way to control the problem is to avoid it.

1. P. Bullock (2005). Encyclopaedia of soils in the environment. 2. V.P. Tchakerian, Hydrology, floods and Droughts/ Deserts and Desertification 3. Desertification: causes, impacts and consequences- Roy.L.Behnke (2017) 4. Amal Kar, Ajai, R.S Dwivedi 5. State of India‘s environment (2017): A Down To Earth Annul 6. Desertification and Land Degradation Atlas of India (Based on IRS AWiFS data of 2011-13 and 2003-05)

PhD Research Scholar, Department of Geography, Rishi Bharthari Matasya University, Alwar, Rajasthan