Widening the scope: linking coastal sedimentation with watershed dynamics in Java, Indonesia

Abstract

Watershed processes and their effects on coasts are shaped by numerous interacting natural and societal factors. The knowledge of these factors and processes is often limited. This makes the field prone to politicisations with debates, research, and interventions being confined to a few selected factors. Debates on the causes of high river sediment loads and coastal sedimentation in Java have focussed on rainfed agriculture on peasants' private lands, while other drivers have been neglected. This has undermined the effectiveness of watershed management. This paper links the sedimentation of the Segara Anakan lagoon on Java's south coast with landscape characteristics and transformations in its catchment. Three-fourths of the lagoon have silted up since 1857/60. This is the result of a much broader range of drivers than commonly assumed to date. In addition to rainfed agriculture on peasants' private lands, these drivers include coffee cultivation, timber extraction, plantation development, and in-migration in the late nineteenth and early twentieth century; erosion on contested state forest and plantation lands; state forest management practices; slope cuts to enlarge agricultural fields; agriculture in riparian zones; erosion from roads, trails, and settlements; river channel and floodplain modifications; and volcanic eruptions. The choice and expectations of societal responses aimed at reducing river sediment loads and coastal sedimentation hence need to be reconsidered, and related debates and research agendas must be broadened.

Intertwined effects of climate and land use change on environmental dynamics and carbon accumulation in a mangrove‐fringed coastal lagoon in Java, Indonesia

“…The relatively low abundance of pollen from cultivated Poaceae and taxa associated with open vegetation during the 1830–1910 drought period appears to be contrary to the large‐scale land use change, marked by a considerable expansion of agriculture in the lagoon's catchment area during this period (Lukas, , ). These land use changes are not reflected in the sediment record, as reduced precipitation must have limited riverine pollen transport into the lagoon.…”

“…It is surrounded by around 9,200 ha of mangrove forest (Ardli & Wolff, 2009), which mainly consists of Rhizophora apiculata, Avicennia corniculatum, A. alba, Nypa fruticans, Sonneratia caseolaris, and Bruguiera gymnorrhiza (Hinrichs, Nordhaus, & Geist, 2009). The SAL catchment comprises an area of around 450,000 ha, with a plain to hilly central river basin, volcanic mountains in the northwest, and sedimentary mountain ranges in the south and northeast (Lukas, 2015b(Lukas, , 2017.…”

“…This means that pollen concentration increases whenever mineral input decreases, and vice versa (Brush, 1989). Therefore, the higher proportion and concen- (Lukas, 2015b(Lukas, , 2017.…”

Green Leadership as an Emerging Style for Addressing Climate Change Issues in Schools

“…Climate change is a universal issue and not only restricted to small island nations. Likewise, coastal management and coastal sedimentation, are influenced by numerous natural and anthropogenic factors, which interact at various intensity over a long span of time (Lukas, 2017). These changes lead to continuous rise in temperature which is very injurious for the mankind as it is directly affects our health.…”

Growth pattern and Condition factor of Mangrove Crab (Scylla tranquebarica) in Segara Anakan Cilacap Regency

“…In Java, the impact of the high sediment load on the coastal area is undeniable, especially in the Segara Anakan Lagoon [7,8]. Mangrove ecosystems in Segara Anakan are experiencing changes in function caused by reduced mangrove forest area, land-use change, sedimentation, and illegal logging.…”