River Kupa

River Kupa belongs to the Black Sea basin. It springs in Gorski kotar in the Risnjak National Park, and flows into the Sava River near Sisak. It is 294 km long, which makes it the third river with the longest watercourse in the Republic of Croatia. Our school, Banija Elementary School, is located in the town of Karlovac. Karlovac lies on four rivers Kupa, Korana, Mrežnica and Dobra. The Kupa river flows near our school so this is the reason why Kupa is our hydrological GLOBE station where we have been conducting measurements for 20 years.

At our measuring station, Kupa is moderately fast in the central part, and slower along the coast. The width of the stream is about 50 meters.

The bottom is sandy and rolling, and in smaller parts muddy, and in some places it is overgrown with underwater vegetation. Along the shore between the stones there are "trapped" twigs and leaves. The shores are the result of anthropogenic influence, overgrown with grass, and the embankment is bordered by a stone wall.

On both sides of the river are the city streets and the area is densely populated and there are built accesses across the embankment to the water.

At our measuring station, once a week, according to GLOBE protocols, we measure water temperature, the amount of dissolved oxygen, pH value, transparency, the amount of nitrite and nitrate ions, alkalinity and electrical conductivity. We regularly enter our data into the GLOBE database and analyze it.

This year, we have measured the physico-chemical parameters on the Kupa River on World Water Day and compared them with the average values ​​in the past 2021. We have compared the obtained results with the limit values ​​from the Decree on Water Classification “Narodne Novine” No. 77/98 and 137/08 and based on these data we have determined the water quality of the Kupa River.

Our desire is to explore the Kupa river in order to improve the quality of life of the community and preserve its natural beauty for future generations. The water quality of the Kupa River is very important for the local community because it is of great tourist importance. We have combined GLOBE protocols with a tourist attraction on river Kupa in order to promote the beauty of river Kupa and to show the importance of GLOBE to local community. CHECK IT HERE --->  https://youtube.com/playlist?list=PLzKFl3S_nsWMXeJprbht9E_NTl8bFGva7  Macroozoobenthos sampling on Kupa river (May 12th, 2021) ---> Mini project with our students

Macroinvertebrates, also known as macrozoobenthos, are a community of macroscopically visible aquatic invertebrates that spend most of their lives on and in the bottom of a waterbody. The presence of certain macroinvertebrate taxa is an indicator of water quality because they are sensitive to changes in pH, dissolved oxygen, temperature, turbidity and other changes in their habitat.

RESEARCH QUESTION

•What will be the water quality of the Kupa river based on the calculated biotic index?

HYPOTHESIS

•Our hypothesis was that the organisms found at the bottom of the Kupa river would show that the Kupa river is naturally clean water or poorly polluted water.

DID WE CONFIRMED OUR HYPOTHESIS? CHECK HERE --->    https://bit.ly/3DSjYW 

MICROPLASTIC IN RIVER KUPA

In 2021, we have started researching microplastics in the Kupa river. Once a month, we have sampled 1000 ml of Kupa river water from the surface layer. Samples were filtered within 24 hours using a Merck-Millipore sterifile Aseptic System filter device with an Ahistrom – Munksjo filter membrane with a pore size of 0.45 µm. After filtration, the membranes were placed in sterile Petri dishes. After that students have observed the samples using the Optika B150 light microscope.

In all observed samples we have found microplastic particles, which is worrying because people catch fish in river Kupa and also use it for agricultural and recreational purposes, which means that microplastic enters the food chain. We want to continue our research and raise awareness of Kupa residents about the presence of microplastics in the Kupa river, educate the local community on methods to reduce the proportion of microplastics in water, and increase people's awareness of the need to reduce using plastic and to recycle it.