ويبدأ سقوط الأمطار من بداية الخريف في شهر تشرين الأول إذ يبلغ (8,32) ملم، ويستمر خلال الشتاء إذ تبلغ أعلى قيمة في شهر كانون الثاني حوالي(34,21)ملم، إلى نهاية الربيع وينقطع سقوط المطر خلال فصل الصيف، وقد تبين من خلال الدراسة بأن أكبر جزيرة هي (23) إذ بلغت(3,866) في عام (1975)، أما أقل جزيرة فكانت جزيرة (26) حيث بلغت مساحتها(0,004) كم2، أكبر مساحة جزيرة هي جزيرة (25) إذ بلغت(12,265) كم2 أما أقل جزيرة فكانت جزيرة (4) حيث بلغت مساحتها(0,010)كم2. تبلغ اطول الجزر(3,356) وهي جزيرة(رقم58) في عام(1975) في حين ازداد هذا الطول للجزر النهرية في عام (2008) ليبلغ (8,116) في جزيرة(رقم18)، بلغت معدل تركيز الجزر عام (1975) حوالي (78,79) وفي عام (2008) تتركز الجزر بمقدار (29) في كل كيلومتر من المجرى، أن درجات التشعب للأعوام بلغت في عام (1975) وهي (7,8) وأقل درجة تشعب بلغت (2,9) في عام (2008).
Geomorphological river islands of the River Tigris between Samarra and the Balad using technology (GIS)
Nibras Abbas Yas
Iraqi University / College of Arts Department of Geography
Abstract The phenomenon of river islands of phenomena affecting the course of the Tigris River, which is evidence of the arrival of the river to the two stages of maturity Late and premature aging as it is made up with the deposition of materials and the lack of speed of the river and the narrow riverbed and the lack of decline river, the study area is located within the course of the Tigris River in the province of Salahuddin between Samarra north to spend the country to the south, as the total length of the course of the Tigris River in the study area distance ( 1,564,29) , km2, for the time confined between (1975 - 2008). The study area is part of the alluvial plain, which is characterized by a lack of variability topographic as a flat area a few rises, study area is located under the influence of the desert climate (hot, dry summers and mild, wet winters), reaches its peak in the months (July, WAP), as the rate of grades Hrarthma (36,2 and 35,2), respectively, and then take then to decline gradually as the amount in the month of September (32,1) and drop to the lowest in a month (January) because of (10,3). It starts from the beginning of the fall of rain fall in the month of October with an average (8,32) mm, and continues through the winter because of a higher value in the month of January around (34,21) mm, to cut off the end of the spring and the fall of rain during the summer, In (1975) was the biggest area of the island is an island (23) as it amounted to (3,866) km2 either less Island was an island (26), where the total area (0004) km2 , the largest area of the island is an island (25) as it was (12,265) km2, either less Island was an island (4) where the total area (0010) km2. Of the longest islands (3,356), an island (No. 58) in the year (1975) while increasing the length of the islands river in (2008) to (8,116) Island (No. 18), hit rate of the concentration of the islands (1975) about (78,79) In (2008) concentrated islands by (29) in each mile of stream, the degree of bifurcation of the year amounted to in (1975), namely, (7,8) and the lower the degree of complexity of (2,9) in (2008).
