Urban Expansion Occurred at the Expense of Agricultural Lands in the Tarai Region of Nepal from 1989 to 2016

Abstract

Recent rapid urbanization in developing countries presents challenges for sustainable environmental planning and peri-urban cropland management. An improved understanding of the timing and pattern of urbanization is needed to determine how to better plan urbanization for the near future. Here, we describe the spatio-temporal patterns of urbanization and related land-use/land-cover (LULC) changes in the Tarai region of Nepal, as well as discuss the factors underlying its rapid urban expansion. Analyses are based on regional time-series Landsat 5, 7 and 8 image classifications for six years between 1989 and 2016, representing the first long-term observations of their kind for Nepal. During this 27-year period, gains in urban cover and losses of cultivated lands occurred widely. Urban cover occupied 221.1 km 2 in 1989 and increased 320% by 2016 to a total 930.22 km 2 . Cultivated land was the primary source of new urban cover. Of the new urban cover added since 1989, 93% was formerly cultivated. Urban expansion occurred at moderately exponential rates over consecutive observation periods, with nearly half of all urban expansion occurring during 2006-2011 (305 km 2 ). The annual rate of urban growth during 1989-1996 averaged 3.3% but reached as high as 8. 09% and 12.61% during 1996-2001 and 2011-2016, respectively. At the district level, the rate of urban growth and, by extension, agricultural loss, were weakly related to total population growth. Variability in this relationship suggests that concerted urban-growth management may reduce losses of agricultural lands relative to historic trends despite further population growth and urbanization. Urbanization and LULC change in the Tarai region are attributable to significant inter-regional migration in a context of poor urban planning and lax policies controlling the conversion and fragmentation of peri-urban cultivated lands. Urban expansion and farmland loss are expected to continue in the future.

Flood Hazard Mapping of a Rapidly Urbanizing City in the Foothills (Birendranagar, Surkhet) of Nepal

“…Urban centers similarly increased in number from 10 to 58 over this period, and to 292 following after the local level reconstruction in 2017. Urbanization has been driven largely by internal migration, in turn sustained by regionally unequal development and economic opportunities [21,26]. Nepal experienced decade long political armed conflict during 1996-2006 [27,28], which displaced or otherwise spurred the migration of rural dwellers to growing cities in search of security.…”

“…As the conflict subsided by 2006, several development activities were advanced throughout the country [29], again concentrating largely in select urban areas. Coincidentally, a peri-urban land market boom resulted in rapid, disorganized settlement expansion at the expense of arable lands [21,29].…”

“…They are effectively used for the LULC analyses [4,[30][31][32][33][34], and flood area mapping. Multi-temporal time series of Landsat images [35] is capable of exploring accurate [36] LULC dynamics in specific time and space [21].…”

“…Total urban area was estimated each observation year to measure the rate of urban expansion [21,37]. The rate of urban expansion describes the average annual growth of urban area during a given period, thus…”

“…A "region of interest" (ROI) boundary representing municipality level study area was delineated for the classification. ENVI software was used to stack, subset, and classify the Landsat images via a maximum-likelihood (ML) algorithm [21,37,38]. A supervised approach with the ML-classifier algorithm was applied for the extraction of LULC.…”