Temporal monitoring of vast sand mining in NW Turkey : Implications on environmental / social impacts 1

6 Loose sand has a wide variety (over 200) of industrial usage where most of the sand is used in 7 infrastructure. Due to its low cost / high benefit nature and international high demand, worldwide 8 examples of excessive sand mining caused complete destruction of habitats and forcing natives change 9 living practices or even to migrate. Sand mining is one of the most controversial and rapidly growing mining 10 sector of the modern world. 11 Sand is rare and regarded as nonrenewable source. The primary source of loose sand are river flood plains 12 and low energy coastal zones, deposited within thousands of years. In the last decade, increasing studies 13 focus on environmental, economic and social impact of sand mining. The most issued problem is 14 quantifying the amount of sand extracted in active depositional environments where indirect estimations 15 and forecasts indicate excessive amount of exploitation. 16 We focus on a long lasting and biggest sand mining zone, Sakarya River at Adapazarı Plain, NW Turkey. 17 Located at close proximity to a high population city, forms a good example to study mining practices by 18 identifying direct and indirect social / environmental impact of sand mining. Mapping and monitoring the 19 last 40 years of the region by remote sensing and by field measurements revealed that, accelerating in the 20 last decade, sand mining practice caused complete destruction of the recent flood plain of the river within 21 ~970 hectares of area. The total amount of exploited material reaches up to ~50 million m, roughly 130 22 million tonnes of sand. 23 Even restricted or declared as illegal, these establishments continue to expand by using several ways. In 24 our case, (1) changing the environment not suitable for cultivation by increased erosion close to mining 25 area and also draining underground water (2) increasing conflicts and stress on habitation by noise 26 pollution and heavy vehicle traffic (3) trapping sand by forming extensive and deep artificial lakes, causing 27 coastal land loss. 28


31
River flood plains and sandy coasts are unique low slope environments developed under interactions 32 between the water and the land and has always been most popular spots for human activities throughout 33 the history. Flood plains stand for a constant fresh water resource and provide well drained land suitable 34 for agriculture. Coastal zones are chosen for harbor settlements since the antiquity and important for 35 transportation, commerce, fisheries and now recreation. 36 37 Rivers are the products of the evolutionary surface processes of the earth and a major actor of hydrological 38 and rock cycle. Although rivers only occupy 0.1% of the earth surface, shape the 71% of the land and supply 39 the 85-90% of total sediment yield to the oceans. Rivers also play an important role on the origin of survival 40 and development of human beings, and closely related to civilization, culture and history. Today river-41 floodplain systems all over the world are greatly affected by human activities serving many functions, 42 hence, they play an important role in people's living and agricultural production (Allan & Castillo, 2007). 43 44 Large scale anthropogenic stress over the river-floodplain systems has been introduced and widely 45 discussed in the recent years (Kondolf, 1994;1997 scouring, degradation, and aggradation; changes in hydrologic regime, etc. (Kondolf, 1994;Kondolf, 1997; 57 Isik et al., 2008). 58 We focus on one of the major recent anthropogenic stress over rivers, sand mining, which stands for the 59 most affective stressor over the river-floodplain system. As a result after thousands years of exploitation 60 and usage, floodplains are now considered as one of the most fragile ecosystems in the world (Winarso,61 and Budhiman, 2001). 62

63
Sand and gravel, are formed within thousands of years of sedimentary processes outlined as 64 weathering/erosion, transportation and finally deposition by rivers. Today, loose sand is considered as an 65 important inorganic industrial raw material with over 200 usage and also forming the major portion of a 66 product namely "aggregate" (Torres et al., 2017). In market terminology, aggregate stands for any 67 inorganic fine-coarse grained material used in construction which covers loose sand, gravel and crushed 68 rocks. From this point forward we will use the term "sand" just for the natural sediment deposited within 69 the river floodplain. 70 Recent data suggests that the demand for sand grows exponentially (UNEP, 2019). This demand is related 71 with the current state of civilization with growing populations, increased urbanization and infrastructure 72 development, resulting consumption to three-fold over the last two decades. Miatto et al. (2017), reported 73 that sand and gravel made up 31.1% and 40.8% of all non-metallic minerals extracted in 2010 respectively. 74 Krausmann et al., (2009) estimate a higher ratio, attributing 65-85% portion of the total inorganic mining. 75 Today, it is estimated that the annual market need for sand is 50 billion tonnes, which corresponds to an 76 average of 18 kg per person per day (UNEP, 2019). This assumption regards sand as the second largest 77 resources extracted and traded by volume after water (Peduzzi, 2014b; UNEP, 2019). However sand 78 extraction, usage and trade are one of the least regulated mining practices, especially in the low to 79 moderate income and developing countries (Torres et al., 2017). Statistics for the total production of sand 80 all over the world is not known for several reasons but can be estimated by production/consumption of 81 anthropogenic material such as concrete production and consumption which is relatively well traced. 82 83 Concrete, the most common modern building material, is a composite material formed of fine and coarse 84 aggregate bonded together with fluid cement. The nominal mix (M-15) composition of concrete is formed 85 of (1:2:4) ratio for cement, sand and crushed gravel/rocks respectively. Therefore it is possible to estimate 86 an annual demand/usage for sand and gravel by using cement production (Kraussman et al. In the USA, for every 1 ton of cement ~10 tonnes of aggregate is used (Figure 1- (Milliman and Syvitski, 1992). In another saying, at our current state 108 impacts" has been submitted for publication as a chapter in "Ecological Significance of River Ecosystems" book (Eds:. Shyam Kanahiy Singh; Arun Lal Srivastav) by Elsevier Publishing.
4 of civilization, we move three times more sediment than all the rivers and glaciers of the world could 109 transport annually (Waters et al., 2016). 110 Sand is a bulky, heavy material. It is cheap to extract and simple to process but expensive to transport. 111 Therefore mines are normally close to where the sand is needed. Rather than there being one global 112 market for sand, the trade is made up of many smaller national and sub-national markets, each with its 113 own demand and supply dynamics and challenges (Peduzzi, 2014). As an example, Singapore increased its 114 national area by over 20% between 1960 and 2017 by land reclamation from the sea thus to be the world's 115 largest importer of sand, mainly from Malesia and Indonesia (Koehnken, 2018). Likewise, the monumental 116 architectural projects at the City of Dubai, UAE; such as The Palm Jumeirah, Palm Jebel Ali and World Island 117 required ~1 BT of sand resulting complete destruction of marine sand sources of the region. Dubai also 118 imported considerable amount of sand from Australia during the construction of Burj Khalifa tower 119 (Peduzzi, 2014a;, which is regarded as the highest building (828 m) in the World. All these exemplify 120 that any urgent and vast need for sand was covered by unregulated means, causing environmental crisis 121 in the close vicinity. 122 River-floodplain systems are a preferred source of sand and gravel for a number of reasons: cities tend to 123 be located near rivers so transport costs are low, the energy in a river grinds rocks into gravels and sands 124 (thus eliminating the costly step of post-mining process, grinding and sorting rock), and the material 125 produced by rivers tends to consist of naturally sorted, angular shaped resilient minerals that are preferred 126 for construction (Kondolf, 1997;Koehnken and Rintoul, 2018). As a result, sand is being increasingly 127 produced through environmentally damaging extractive practices in sensitive river ecosystems (Koehnken 128 et al., 2020). 129

Environmental and Social Impacts of Sand Mining
River-floodplain systems, by the nature of formation, are very limited and narrow environments with a 132 dynamic equilibrium between river flow, river slope, sediment supply and sediment size (Lane, 1954;133 Langbein & Leopold, 1964). These components can be depicted as a balance to demonstrate how a river 134 channel will respond to changes to any of these factors. Any unscientific effort concerning river-floodplain 135 environment result in destruction of a large habitat for long distances, affecting other interconnecting 136 systems, located dozens of kilometers downslope or upslope. The response of river ecosystems to sand 137 mining is complex, with no one simple cause-effect model applicable to all systems. Channel incision is 138 the most common physical change, but other responses are highly variable and linked to the inherent 139 characteristics of the river system and other stressors (Koehnken and Rintoul, 2018; areas, leading to reduced deposits in river deltas and accelerated beach erosion (Kondolf, 1997). The state of sand production in Turkey, likewise to the world, is neither regulated nor measured. Limited 190 and discontinuous statistics declared by State Statistics Institution (TURKSTAT) states that the aggregate 191 industry occupies 45% of the total mining products of Turkey. In 2000, the total amount of sand/gravel 192 production reaches up to 90 MT. A report by İstanbul Chamber of Commerce, declared the composition 193 of aggregate used in concrete as 17% riverine sand and crushed rock to 83% (Alp, 2004). According to our 194 previous assumption, the total amount of sand required for concrete production would be estimated as 195 impacts" has been submitted for publication as a chapter in "Ecological Significance of River Ecosystems" book (Eds:. Shyam Kanahiy Singh; Arun Lal Srivastav) by Elsevier Publishing.

6
~100 MT. This number should point out minimum where riverine mining also extracts gravel which is also 196 used for producing crushed rocks extending the total estimation to ~200 MT per year. Turkey also exports 197 sand abroad with five year average to ~60 kT (Chatham House, 2020). 198 Sand mining was traditionally carried by construction related state organizations (municipalities, state 199 hydraulic works and motorway directorates) which have had legal means and equipment for sand mining, 200 but for the last 20 years private companies took the lead parallel to cement and aggregate production 201 (Alp, 2004). As a consequence, today there are sand mining practices along almost every minor and major 202 rivers of Turkey, especially near the developing cities and along major construction projects. Quaternary alluvium which cover 10% surface area of the whole country. The potential of riverine loose 210 sand deposits (flood plain) only corresponds to 1%. Green shaded area is the Sakarya River basin where its 211 lower reaches, the city of Sakarya (Figure 2 B), a fast growing metropole with 1 M residents, claims 18% of 212 Turkey's total sand production (Yüksel and Sandalcı, 2007). 213 This study focuses on temporal monitoring of intense sand mining operations within a relatively small and 214 narrow (20 km 2 ) zone which led to total destruction of a river / floodplain system in 40 years. We wish to 215 address and stress out the effects of uncharted sand mining causing social, ecological and environmental 216 problems. 217

218
The focus area which is subject to intense sand mining, is located at the southern part of Adapazarı Plain 219 and in between two river type hydroelectric power plants (HPP), one at the northern outlet of the Geyve 220 Gorge and other near the city center of Sakarya ( Figure 2B and Figure 3a). The length of the study area is 221 15 km, covering 20 km 2 surface area. 222

223
Sakarya River, flowing for ~824 km, with drainage basin ~63350 km 2 , covers 8% of the total surface area 224 of Turkey (Figure 2a). After running through series of narrow gorges formed within the western Pontide 225 mountain range, the lower reaches of the river crosses Pamukova and Adapazarı tectonic basins formed 226 on the North Anatolian Fault Zone ( Figure 2B). The river reaches to the Black Sea forming the wide but 227 narrow Karasu Delta ( Figure 2B). The long term mean discharge  of the river is measured as 228 124 m 3 /s, while hydrological extremes (500 m 3 /s) in between 1963-1970 at Doğançay station at the 229 northern outlet of the Geyve Gorge ( Figure 3A). Sakarya River shares 15.6% portion of Turkey's total 230 riverine sediment yield with 180-200 T/km 2 , carrying ~12 MT suspended sediment to the Black Sea 231 annually (Milliman and Syvitski, 1992;Öztürk, 1996). The discharge and sediment yield characteristics of 232 the river reduced significantly after sequent construction of Sarıyar (1956)

295
All the dataset described above was gathered to build up a temporal database in ArcGIS ™ environment. 296 The base (pre-sand mining era) map was produced by digitizing the geomorphological map drawn by T. 297 Bilgin (1984). The river/floodplain and terrace staircases was classified according to rtk-GPS profiling and 298 field observations where the thickness of each sedimentary unit is determined (Erturaç et al., 2019). The 299 initial land use of the study area was determined from 1975 keyhole imagery. For achieving the study goal, 300 the temporal monitoring of the sand mines, we choose manual classification during the digitization process 301 where the spatial (Landsat) and spectral (Keyhole and Google) resolution of the image database was not 302 effective. The areal coverage and estimated volume for each mine during each time-step is calculated in 303 GIS environment. 304 All digitized polygons are classified according to classes of sand mining practices from remotely sensed 305 imagery for each focus year. The area (a) of the polygons are calculated in hectares (1 ha= 0,01 km 2 = 10000 306 m 2 ), and extracted volume (v) of sediment from a sand mine / artificial lake is calculated in cubic meters 307 (a × h) where h is determined by using the determined relative height of the terrace and estimated lake 308 depth. The geochemistry of Adapazarı fluvial sediments are determined by ICP-AES analysis (ALS Global) 309 of 14 samples which yielded average composition of major oxides as SiO2 (52.7%), Al2O3 (11.3%); CaO 310 (11.3%), Fe2O3 (4.7%), MgO (2.3%) and LOI (12.2%). This composition indicates the average density (d) of 311 Sakarya sediments as 2.6 g/cm 3 . We calculated the total weight (w) of extracted sand by using the 312 calculated volume and estimated density. 313

314
The results of this study details two interconnected topics: (1) The geometry and extend of the terrace 315 staircases (TSC) and the modern floodplain of the Sakarya River at the study area ( Figure 3) and (2)  316 temporal expansion of the sand mines and relevant statistics (Figure 4). 317 The geometry and the thickness of the terraces (T2, T1 and T0) varies significantly along the ~10 km 318 course of the Sakarya River at the study area. We used six topographic profiles derived from rtk-GPS and 319 UAV-DSM ( Figure 3B) to determine the sediment thickness of the excavated terrace which aided to 320 calculate total volume of sediment removed by sand mining. Qkpc, hence will be called as substratum from this point forward. The terrace T4 deposited in between 84-330 72 ka and stands at +55 m afp (Erturaç, 2020). It is observed covering a wide flat area, at the southeastern 331 side of the river, however the terrace section was only observable topping Karapürçek formation at a 332 former sand quarry ( Figure 3A). The measured thickness of the terrace reaches 8 meters. The terrace T3 333 started to form at 40 ka until 30 ka. It stands at +21.5 m afp and max observed thickness is 8-10 m. This 334 terrace step forms a wide surface at the western part of the river, occupied by settlements (Kirazca and  335 Karaçam, Figure 3)  along the river channel, but reaches up to 1 km in width at an abandoned meander, near Adliye-Ahmediye 354 villages (Figure 3). T1 stands at 2-2.5 m relative elevation ( Figure 3B). The majority of the terrace strata 355 are formed of coarse-fine grained cross laminated sand bars and horizontal silty-clay layers with max 356 observable thickness is 2.5 m. 357 Although these steps are distinct and easily separated with each other at the study area, they fade away 358 and coincide with the T2 surface at the center of the Adapazarı Plain, where Sakarya River forms a deeply 359 incised channel. 360 The modern floodplain of the Sakarya River is today completely destructed by sand mining. However it is 361 possible to map the undisturbed meandering geometry and extend of the floodplain by using 1975 Keyhole 362 (Corona) imagery. The river had a 20 km channel length in 13 km total distance forming 10 meanders 363 where sinuosity ratio is calculated as 1.5. The average channel width was 70 m (standard deviation: 20 m), 364 meander amplitude is 2.4 km, wavelength 2.6 km, and radius of curvature is ~ 500 m ( Figure 3A). The 365 complete section of the T0 can be observed at the outlet of the Geyve Gorge, at the southwest corner of 366 the study area, where the natural channel is lowered ~5 m during the construction of the Doğançay 367 hydroelectric power plant (HPP). The terrace consist of ~2 meters of bedload deposits overlain by 4 m fine 368 grained sediments where a tree trunk in between is 14 C dated to 750 yr/BP (Erturaç et al., 2019). 369

Sakarya Sand Mines (SSM)
370 In this study we classified the sand mines according to the excavation practices which varied through time 371 and space ( Figure 3A and B). The first type is "sand mine" which stands for total excavation of the terrace 372 step, varying in areal extend but through whole depth until the lithified clastic substratum (Qkpc). In many 373 cases these sand mines, especially operating on T1 surfaces, later modified into new facilities such as 374 greenhouses or industrial facilities or factories. The second type is "artificial lake" which indicates deep 375 excavation, either operating on T1 or T0 surfaces, reaching below the water table therefore become a lake. More recent and advanced mining practices are introduced operating close to the main river channel. In 382 this case, the T0 surface is completely destroyed and excavated deep inside the substratum. The miners 383 continuously divert the river channel in seasonal manner by forming artificial levee(s) forming series of 384 interconnected lakes adjacent to the channel. This type is named as "sand traps" as the main aim is to trap 385 the coarse sediment yield of the river carried during the high flow period (winter) and harvest during the 386 low flow period (summer). This type of mining practice is most common to the south as the T0 is narrower 387 and the terraces are mostly occupied by settlements or cultivated. 388

389
The natural flood plain of the Sakara River is completely destructed and altered at the study area. In order 390 to monitor the changes through time, we first used the satellite imagery (1975,1980) and the 1/25k scale 391 topographic map (1959) and geomorphological map of pre-mining era (Bilgin, 1984), to map the land use 392 and original physiography of the vicinity.

447
There are two general types of sand mining practices at the study area ( Figure 5): (1) using potential of the 448 natural terraces T2, T1 and T0, by excavating the terrace completely and also deep trenching under the 449 water level forming artificial lakes. This practice took place in the first and second phases (and zones) of 450 sand mining and (2) excavating sand traps to harvest the annual sand yield of the river and also dissolving 451 the sand of the substratum (Qkpc) by freshwater input. This practice was carried out in zone III and IV and 452 after 2012 and still operational. The mining facilities continuously alter and excavate deep into the river 453 channel, extract sediment from terraces, sand traps and also loosened material from Qkpc ( Figure 5). Post-454 operations including sieving the extracted material in order to separate sand and gravel/blocks, building 455 up large scale piles of blocks and artificial levees are widely scattered within the active zones ( Figure 5). 456 closed their roads to avoid the trucks traffic, increasing stress between the miners and the locals. 484

485
We have detailed the history of the Sakarya Sand Mine (SSM), located in a highly industrialized and 486 populated zone of Turkey. Laying as an example for sand production practices at a growing actor in global 487 cement / aggregate production, consumption and trade. The trend and total amount of sediment 488 extracted is monitored by using multi-temporal satellite imagery due to the lack of relevant data regarding Considering the annual sand/gravel production of Turkey is estimated as 65 MT, we may conclude that 494 SMM (20 km 2 ) covers the 7-8% of the total demand. The result is the total destruction of the flood plain 495 which has direct effects on environment, agriculture and local residents, and causing accelerated coastal 496 land loss. 497 Available literature on sand and gravel mining represents and stresses out numerous common concerns 498 on direct impact and need for action. This is a global problem and effects river ecosystems, people and 499 economy on various scales. Loose sand and gravel (aggregate) mining is defined as one of the main 500 sustainability issues of the 21 st Century (UNEP, 2019). The accelerating rate of urbanization causes increase 501 in construction of buildings and infrastructure, driving need for aggregate. As a result, the civilization now 502 acts as a major earth surface process, eroding, moving, and depositing sediment during the Anthropocene 503 epoch, rapidly depleting natural resources. Sand is an extremely rare, and definitely not an infinite source.

504
Global examples lay out that the sand mining has always been aggressive, benefiting from the luxury of 505 being prerogative due to urgent demands, unregulated, practice irresponsible to the natural environment 506 and local residents, directly causing stress and conflict. Complex questions arise on how to deliver on 507 ecosystem and biodiversity conservation goals while necessary improvements in transport, infrastructure, 508 housing and living standards are looming (UNEP, 2019). Urgent actions are needed for (1) applying or 509 extending available national regulations and limitations to curb irresponsible and illegal extraction for 510 sand, (2) reducing sand demand by investing research for finding means and ways for using recycled / 511 alternative material to use as aggregate, (3) imposing dialogue between key players, and stakeholders in 512 the sand value chain based on transparency and accountability (UNEP, 2019). 513