Juha Sarkkula

• Finnish Environment Institute

The Upper Mekong Basin is undergoing extensive hydropower development and its largest dams have recently become operational. Hydropower is built to improve the regional energy supply, but at the same time, it has considerable transboundary impacts on downstream discharge regime and further on aquatic ecosystems, riparian livelihoods and food securi...

The Tonle Sap Lake of Cambodia is the largest freshwater body of Southeast Asia, forming an important part of the Mekong River system. The lake has an extremely productive ecosystem and operates as a natural floodwater reservoir for the lower Mekong Basin, offering flood protection and assuring the dry season flow to the Mekong Delta. In light of t...

The Tonle Sap Lake in Cambodia is a dynamic flood-pulsed ecosystem that annually increases its surface area from roughly 2,500 km(2) to over 12,500 km(2) driven by seasonal flooding from the Mekong River. This flooding is thought to structure many of the critical ecological processes, including aquatic primary and secondary productivity. The lake a...

Continuous monitoring of turbidity, dissolved oxygen (DO), conductivity, temperature, and fluorescence was done at five locations on the Tonle Sap Lake and the Mekong–Bassac Rivers near Phnom Penh, Cambodia, between 2004 and 2010 using autonomous datasondes. Seasonal, daily, and spatial trends were clearly identified in the data and were related to...

Hydraulic erosion of bank toe materials is the dominant factor controlling the long-term rate of riverbank retreat. In principle, hydraulic bank erosion can be quantified using an excess shear stress model, but difficulties in estimating input parameters seriously inhibit the predictive accuracy of this approach. Herein a combination of analytical...

Riverbank erosion is a natural process, but often human activities can have a significant impact on the rates of morphological change. This paper aims to assess bank erosion problems in the Vientiane–Nong Khai section of the Mekong River, where the Mekong borders Thailand and Lao PDR. The study provides new and more accurate information about recen...

It has been claimed that Tonle Sap Lake is rapidly filling with sediment as a result of increasing sediment yields from the catchment. Infilling of the lake basin would have serious implications for the magnitude of flooding in central Cambodia and the Mekong Delta region and threaten the lake's unique ecosystem. In this article, we synthesize the...

Rapid development in the upper reaches of the Mekong River, in the form of construction of large hydropower dams and reservoirs, large irrigation schemes, and rapid urban development, is putting water resources under stress. Recent studies have concluded that these developments will lead to flow alterations in the Mekong River. These flow alteratio...

River bank erosion is the product of a suite of specific processes that together contribute significantly to the sediment yielded from river catchments. Many studies have emphasised that hydraulic erosion of bank-toe materials may exert a dominant influence on the long term rate of river bank retreat. Fluvial bank erosion rates are normally quantif...

A network of Hydrolab Datasonde 4a's was operated in the flooded forest fringe of the Tonle Sap Lake, near Pursat, and the Chaktomuk Junction at Phnom Penh, between 8/1/05 and 1/22/06. Samples also were collected for non-destructive image analysis of suspended sediment size. The Hydrolabs successfully tracked the freshwater flood pulse and expansio...

Are models useful for management and decision making on water resources? Are the efforts put into them justified? In this chapter we argue that mathematical modeling is one of the few options available to look at the questions of future changes and impacts of human activity on water resources. Models and their results, however, are often mistrusted...

The ecosystem of the Tonle Sap Lake is driven by the monsoon floods of the Mekong River. This unique pulsing system together with high annual sediment and nutrient fluxes from Mekong makes the Tonle Sap one of the most productive freshwater ecosystem in the world. However, local and upstream developments have increase the environmental pressure and...

Integrated Water Resources Management has been identified as one of the basic water resources related policy approaches in several recent important commitments and recommendations including the Johannesburg Summit and World Water Forums. Recognizing that IWRM is largely still a theoretical concept with not much sound scientific research, our object...

The ecosystem of the Gulf of Finland is currently dominated by internal phosphorus loading from sediments. The internal load is highly redox sensitive, and its successful modelling on basin-wide scale requires a simplified description of the sediment process. We present here an approach in which redox-sensitive sediment processes are directly linke...

Abu-Qir Bay is a semicircular basin in the eastern part of Alexandria City, Egypt. The Bay has a maximum depth of 15 m, and surface area of 500 km2. The bay is suffering from a serious pollution problem caused by the inflow of brackish water from Lake Edku and the poor-quality water discharged from the Rosetta Nile branch. The variations in wind re...

A hydrodynamic and water quality model were applied to a coastal bay east of Alexandria City in the southeastern sector of the Mediterranean Sea subjected to industrial, agricultural and sewage discharge to determine the transport and dispersion of Total Lead (PbTOT) and Dissolved/Dispersed Petroleum Hydrocarbon (DDPH). The water circulation in the...

Tonle Sap Lake in Cambodia is the largest permanent freshwater body in South-east Asia. The 3D hydrodynamic and water quality model has been set up for the lake and its floodplains to understand the ecosystem and geomorphological processes, and the possible changes caused by the Mekong upstream developments as dams and reser-voirs.

In many coastal environments over-fertilization is an impediment to fishing and tourism. The Gulf of Finland (Baltic Sea) is one example of where the environmental conditions have not improved in spite of lower land input of nutrients. The reasons for this are investigated in an ongoing project in which a unique combination of traditional and novel...

Helsinki is located on the southern coast of Finland by the Baltic Sea. The ecological state of the archipelago in front of Helsinki is affected by several factors. The effects of local point and scattered loads are mixed with the transboundary effects from neighbouring countries and atmospheric deposition. Municipal waste waters of 800 000 inhabit...

We have used a simple 3D-ecosystem model to describe nutrient dynamics and biomass production in the Neva Bay off St. Petersburg.The River Neva is responsible for carrying the waste waters of St. Petersburg to the Gulf of Finland. Literature values ofchlorophyll- a concentrations and satellite images have been used for model validation. The results...

Since most biological and chemical processes in some way involve oxygen, it is the single most important parameter to measure in marine biology and chemistry. For environmental reasons, it is also critical to monitor oxygen in areas where the supply is limited compared to the demand (e.g., fjords, around fish farms, in shallow coastal areas, in lak...

The claim for integrated and holistic water resources management in a river basin scale has become an ingrained phrase in all agendas, yet the practice still awaits the indispensable progress into the integrated direction. Attempts are many, though. This paper documents the ongoing work of developing integrated assessment methodologies to the Mekon...

Figure 1. Lower Mekong Basin with Tonle Sap Lake. Dry season lake (~1.5 m above the mean sea level (a.m.s.l.)) is presented as dark blue while the flood plain of the year 2000 flood is presented as lighter blue (~10.3 m a.m.s.l.). The 2-year project "Modelling of the Flow Regime and Water Quality of the Tonle Sap" (MRCS/WUP-FIN) has helped the MRC...

The Gulf of Finland is one of the most eutrophied areas of the Baltic Sea. The major part of the nutrient load enters the sea outside Finnish borders from the metropolis of St. Petersburg and the river Neva. Finnish local authorities are facing a difficult task of defining water protection measures, when the effects of local measures have to be wei...

The paper deals with a 100 ha wetland in an estuary of the capital area of Finland. The area has gone through major changes in the last decades due to land based and river bome nutrient loads, resulting in unfavourable living conditions for aquatic birds. In order to restore the overgrown areas, opening inner ponds and brook channels by dredging is...

Boreal Environment Research, vol 6, nr 2, p. 131-146, 1239-6095 The effects of nutrient load reductions on the biomass of N-fixing cyanobacteria were evaluated in the scale of the Gulf of Finland. The two analysed reduction scenarios were Finnish national agenda and the improvement of phosphorus removal in the present purification plants of St. Pet...

The three-dimensional water quality and flow model was used to simulate phytoplankton biomass and dissolved nutrient concentrations in the Gulf of Finland. In the model, transport of nutrients is based on calculated wind and river flow-induced currents. Water quality data from two points off the Finnish coast were used for the model calibration.Nit...

Environmental Modelling & Software, 1364-8152, vol. 13, nr. 5-6 , 503-509 One of the most visible symptoms of eutrophication in the Gulf of Finland is blooms of unattached filamentous algae. This decomposing algal biomass causes serious nuisance problems for recreational uses of the coastal zone, particularly when cast ashore. The nutrient availabi...

Water Poll. Res. J. Canada, vol. 29, nr. 2/3, 343-363 Measuremrnt programs and model simulations of hydrodynamics and ecology of the Gulf of Finland, asub - basin of the Baltic Sea, have been carried out from the 1970s. The measurements indicate that there exists a wind - independent background current in the gulf. A 2.5-D baroclinic, prognostic, h...

Trophic conditions and hydrography of the whole north-east Gulf of Finland in both the Finnish and the Russian waters, including the Neva Estuary, were for the first time extensively explored in August 1990. The Neva Estuary was defined on the basis of hydrographical and geomorphological characteristics. The results revealed extensive and strong in...

As a continuation and improvement of the past measuring and modelling activity, extended current measurements and joint numerical modelling were carried out in three shallow lakes in Hungary and in Finland, focusing at the near shore flow phenomena. The main goals of the investigations were to explore wind induced flow characteristics and the deman...

Systems Analysis Applications to Water Research - A Soviet-Finnish Project. Ed. Timo Huttula. Publ. Water and Environment Research Institute No. 3, 55 - 61

An ecological model, coupled with a hydrodynamic one, is applied to Lake Näsiselkä, the southernmost sub-basin of Lake Näsijärvi, Central Finland. Its surface area is 93 km2, mean depth 15 m, maximum depth 61 m, and through-flow 64 m3/s. The transport velocities to the ecological model are computed with a three-dimensional hydrodynamic sub-model. I...

A two-dimensional horizontal hydrodynamical model has been used to estimate the changes that a harbour road will cause in the water exchange of an estuary. The research area has been the Kokemäenjoki river estuary on the coast of the Gulf of Bothnia in western Finland. The numerical model has been verified on the basis of a regression model describ...

The Tonle Sap Lake and floodplains in the heart of Cambodia contain the largest continuous areas of natural wetlands habitats remaining in the Mekong system, while being the largest permanent freshwater body in Southeast Asia. Tonle Sap is a crucially important source for food and living in Cambodia. More than one million people live in the immedia...

Natural resources are vital to people along the Mekong as the livelihood of most of the people depend to large extent on natural ecosystems, especially in the poorest countries Cambodia and Lao PDR. One of the most important parts of the Mekong system is the Tonle Sap Lake in Cambodia being the main source of animal protein for Cambodia and working...

Biotieteen päivät. Publications of the University of Kuopio. Abstract, 13

4th Int. Conf. on State-of-the-Art in ecological modelling. Tsukuba, Ibaraki, Japan, 20 - 24 Aug. 1984

Vesihallituksen monistesarja 252

Andra svensk-finska seminariet om Bottniska viken, Luleå, Sverige, 16-17 juni 1981 = Second Swedish Finnish Seminar on the Gulf of Bothnia, Luleå, Sweden, June 16-17, 1981: ed.: Hans Cederwall, SNV PM 1618, 38-42 Svensk-finska seminariet om Bottniska viken. 2 Luleå 1981

Andra svensk-finska seminariet om Bottniska viken, Luleå, Sverige, 16-17 juni 1981 = Second Swedish Finnish Seminar on the Gulf of Bothnia, Luleå, Sweden, June 16-17, 1981: ed.: Hans Cederwall, SNV PM 1618, 249-253 Svensk-finska seminariet om Bottniska viken. 2 Luleå 1981

Publ. Water Res. Inst. National Board of Waters, Finland, nr. 68, 84-90

Vizügyi Közlemenyek = Hydraulic engineering, ISSN 0042-7616, vol. 69, nr. 3, 51-465

Vituki monographies, ISSN 0134-1316 ; 49 Pages: 39 p.

Vesi- ja ympäristöhallinnon julkaisuja = Publications of the Water and Environment Administration, ISSN 0786-9592 ; 50 Pages: 137 p. In the autumn of 1987 exceptionally heavy blooms of blue-green algae, especially Microcystis aeruginosa, caused problems to fishery and recreation along the Finnish coast in the eastern Gulf of Finland. Subsequently a...

Hirvi, Juha-Pekka (ed.) Operatiivinen ajelehtimis- ja kulkeutumismalli merialueille, Vesi- ja ympäristöhallinnon julkaisuja - sarja A 134, ISSN 0786-9592, 9-14

Hirvi, Juha-Pekka (ed.) Operatiivinen ajelehtimis- ja kulkeutumismalli merialueille, Vesi- ja ympäristöhallinnon julkaisuja - sarja A 134, ISSN 0786-9592, 77-93 The data from drifting tests, current measurements, oil combatting exercises and well documented sea accidents was used for testing, calibration and to compare the models. The results and e...

Proc. of the Int. Conf. on oil terminals, shipping and off - shore activities in the eastern Baltic, Tallinn, 90-91

Sustainable water management. Finland's experiences. Helsinki, Finnish Environment Institute & Ministry of the Environment. 2 p.

Finnish Civil Engineering/Rakennustekniikka, vol. 56, nr 4, p. 54-56, 0033-913X

Tr.: Sgornik tezisov : VI Mezdunarodnogo ékologiceskogo foruma "Den baltijskogo morja" [21-23 marta 2005 g. Sankt-Peterburg]. Sankt-Peterburg, Baltic Marine Environment Protection Commission - Helsinki Commission (HELCOM). C. 72, 74, 76. VI Mezdunarodnogo ékologiceskogo foruma "Den baltijskogo morja", 21-23 marta 2005 g. Sankt-Peterburg

Tr.: Sgornik tezisov : VI Mezdunarodnogo ékologiceskogo foruma "Den baltijskogo morja" [21-23 marta 2005 g. Sankt-Peterburg]. Sankt-Peterburg, Baltic Marine Environment Protection Commission - Helsinki Commission (HELCOM). C. 73, 75. VI Mezdunarodnogo ékologiceskogo foruma "Den baltijskogo morja", 21-23 marta 2005 g. Sankt-Peterburg

In: IMEMS 2005 : The 8th International Marine Environmental Modeling Seminar. Helsinki, Finland, 23-25 August, 2005. Abstract Proceedings. [Helsinki], SINTEF, SYKE. P. 9. IMEMS 2005 : The 8th International Marine Environmental Modeling Seminar. Helsinki, Finland, 23-25 August, 2005

Publications of the Water and Environment Research Institute, 0783-9472 ; 7 Pages: 91 s. The dynamics of the Bothnian Bay was studied mainly by means of numerical models. The model results were supported by flow velocity measurements and by water quality components sampled for more than twenty years in the research area. Prior to the study an exten...