He turneth the desert into a pool of water This change, in contrast with the former, places the miraculous power of God in a more luminous position. Because, were the fields ceasing to be so productive as in former times, men of the world, as was common of old, would attribute this to the frequent crops which exhausted their productive power. But whence is it that parched grounds become so fruitful, that one would almost say that the atmosphere, as well as the nature of the soil, had undergone a change, unless it be that God hath there put forth a wonderful display of his power and goodness? Wherefore, the prophet very justly says, that the deserts were turned into pools of water, so that populous cities may rise up in waste and uncultivated places, where once there was not a single cottage. For it is as improbable that the nature of the soil is changed, as that the course of the sun and stars is changed. The clause, the hungry are filled, may mean, either that they themselves, after considerable privations, have got what may supply their need, or that those poor persons, living in a country where they cannot longer find daily bread, being constrained to leave it, and to seek a new place of abode, are there bountifully supplied by God. I am rather disposed to think, that this clause refers to what frequently occurs, namely, that the famishing, whose wants the world refuses to supply, and who are expatriated, are comfortably accommodated in these desert places, where God blesses them with abundance. The passage which I have translated, fruit of the increase, is, by not a few Hebrew expositors, considered as a repetition of two synonymous terms, and are for supplying a copulative conjunction, making it, fruit and increase But it was rather the intention of the prophet to refer to fruit yielded annually; as if he said, the fertility of these regions is not temporary, or only for a few years, it is perennial. For tvv'vt, tebuaoth, is the term which, in the Hebrew, denotes full-grown fruit annually produced by the earth. And when he says, that the new settlers sow and plant, he gives us to understand, that, prior to their arrival, cultivation was unknown in these places, and, consequently, in becoming so unusually fertile, they assumed a totally different aspect. And, in fine, he adds, that it was entirely owing to the Divine blessing that those who were once oppressed with poverty and want are now daily increasing in the good things of this life.

He turneth the wilderness into a standing water - A pool; a lake. See the notes at Isaiah 35:6-7.
And dry ground into water-springs - Not merely watering it with rain from heaven, but causing gushing fountains to break forth, and to flow continually, diffusing fertility and beauty everywhere.

He (q) turneth the wilderness into a standing water, and dry ground into watersprings.
(q) For the love that he bears to his Church, he changes the order of nature for their convenience.

He turneth the wilderness into a standing water,.... On the other hand, when it is the pleasure of God, a country uncultivated and like a desert, he makes it fruitful as one that is well watered and tilled; as this country of ours, and the land in America, once waste places, now fruitful ones.
And dry ground into water springs: which is expressive of the same thing, and may he figuratively understood of the Gentile world; which, before the coming of Christ, and the preaching of the Gospel, and the pouring down of the Spirit, was like a wilderness and dry ground; but now watered with the word and ordinances, and the grace of God, and in many places has become fruitful in grace and good works. The Targum prefaces this verse thus,
"when they return unto the law, he turneth, &c.''

Water - Into a well - watered and fruitful land.